diff --git a/EvidenceBase.cpp b/EvidenceBase.cpp
index f665c5c2..902b6539 100644
--- a/EvidenceBase.cpp
+++ b/EvidenceBase.cpp
@@ -47,7 +47,7 @@ fiftyoneDegreesEvidenceKeyValuePairArray* EvidenceBase::get() {
 		for (map<string, string>::const_iterator iterator = begin();
 			iterator != end();
 			iterator++) {
-			EvidencePrefixMap *map = 
+			EvidencePrefixMap* map =
 				EvidenceMapPrefix(iterator->first.c_str());
 			if (map != NULL && isRelevant(map->prefixEnum)) {
 				EvidenceAddString(
diff --git a/EvidenceBase.hpp b/EvidenceBase.hpp
index c523ae62..dad5cea6 100644
--- a/EvidenceBase.hpp
+++ b/EvidenceBase.hpp
@@ -71,9 +71,9 @@ namespace FiftyoneDegrees {
 			 * @{
 			 */
 
-			/**
-			 * Construct a new instance containing no evidence.
-			 */
+			 /**
+			  * Construct a new instance containing no evidence.
+			  */
 			EvidenceBase();
 
 			/**
@@ -87,12 +87,12 @@ namespace FiftyoneDegrees {
 			 * @{
 			 */
 
-			/**
-			 * Get the underlying C structure containing the evidence. This
-			 * only includes evidence which is relevant to the engine. Any
-			 * evidence which is irrelevant will not be included in the result.
-			 * @return pointer to a populated C evidence structure
-			 */
+			 /**
+			  * Get the underlying C structure containing the evidence. This
+			  * only includes evidence which is relevant to the engine. Any
+			  * evidence which is irrelevant will not be included in the result.
+			  * @return pointer to a populated C evidence structure
+			  */
 			fiftyoneDegreesEvidenceKeyValuePairArray* get();
 
 			/**
@@ -101,9 +101,9 @@ namespace FiftyoneDegrees {
 			 * @{
 			 */
 
-			/**
-			 * Clear all evidence items from the instance.
-			 */
+			 /**
+			  * Clear all evidence items from the instance.
+			  */
 			void clear();
 
 			/**
@@ -118,7 +118,7 @@ namespace FiftyoneDegrees {
 			 * @param last item to remove
 			 */
 			void erase(iterator first, iterator last);
-			
+
 			/**
 			 * @}
 			 */
@@ -133,7 +133,7 @@ namespace FiftyoneDegrees {
 			virtual bool isRelevant(fiftyoneDegreesEvidencePrefix prefix);
 		private:
 			/** The underlying evidence structure. */
-			fiftyoneDegreesEvidenceKeyValuePairArray *evidence;
+			fiftyoneDegreesEvidenceKeyValuePairArray* evidence;
 		};
 	}
 }
diff --git a/evidence.c b/evidence.c
index c53539b6..ca415233 100644
--- a/evidence.c
+++ b/evidence.c
@@ -24,15 +24,22 @@
 #include "fiftyone.h"
 
 typedef struct evidence_iterate_state_t {
-	fiftyoneDegreesEvidenceKeyValuePairArray *evidence;
+	EvidenceKeyValuePairArray *evidence;
 	EvidencePrefix prefix;
 	void *state;
-	fiftyoneDegreesEvidenceIterateMethod callback;
+	EvidenceIterateMethod callback;
 } evidenceIterateState;
 
+typedef struct evidence_find_state_t {
+	Header* header; // Header to find
+	EvidenceKeyValuePair* pair; // Pair found that matches the header
+} evidenceFindState;
+
 static EvidencePrefixMap _map[] = {
-	{ "server.", sizeof("server.") - 1, FIFTYONE_DEGREES_EVIDENCE_SERVER },
-	{ "header.", sizeof("header.") - 1, FIFTYONE_DEGREES_EVIDENCE_HTTP_HEADER_STRING },
+	{ "server.", sizeof("server.") - 1, 
+	FIFTYONE_DEGREES_EVIDENCE_SERVER },
+	{ "header.", sizeof("header.") - 1, 
+	FIFTYONE_DEGREES_EVIDENCE_HTTP_HEADER_STRING },
 	{ "query.", sizeof("query.") - 1, FIFTYONE_DEGREES_EVIDENCE_QUERY },
 	{ "cookie.", sizeof("cookie.") - 1, FIFTYONE_DEGREES_EVIDENCE_COOKIE }
 };
@@ -45,8 +52,9 @@ static void parsePair(EvidenceKeyValuePair *pair) {
 	case FIFTYONE_DEGREES_EVIDENCE_QUERY:
 	case FIFTYONE_DEGREES_EVIDENCE_COOKIE:
 	default:
-		pair->parsedValue = pair->originalValue;
-		pair->parsedLength = strlen(pair->parsedValue);
+		// These are string prefixes so just copy over the original values.
+		pair->parsedValue = pair->item.value;
+		pair->parsedLength = pair->item.valueLength;
 		break;
 	}
 }
@@ -54,15 +62,19 @@ static void parsePair(EvidenceKeyValuePair *pair) {
 // If a string comparison of the pair field and the header indicates a match
 // then set the header to avoid a string comparison in future iterations.
 static void setPairHeader(EvidenceKeyValuePair* pair, Header* header) {
-	if (pair->fieldLength == header->length &&
-		StringCompareLength(pair->field, header->name, header->length) == 0) {
+	if (pair->item.keyLength == header->nameLength &&
+		StringCompareLength(
+			pair->item.key, 
+			header->name, 
+			header->nameLength) == 0) {
 		pair->header = header;
 	}
 }
 
 /**
  * Iterate through an evidence collection and perform callback on the evidence
- * whose prefix matches the input prefixes.
+ * whose prefix matches the input prefixes. Checks the linked list of evidence
+ * arrays to ensure these are also processed.
  *
  * @param evidence the evidence collection to process
  * @param prefixes the accepted evidence prefixes
@@ -75,12 +87,14 @@ static uint32_t evidenceIterate(
 	int prefixes,
 	void* state,
 	EvidenceIterateMethod callback) {
-	uint32_t i = 0, iterations = 0;
-	const uint32_t count = evidence->count;
+	uint32_t index = 0, iterations = 0;
 	EvidenceKeyValuePair* pair;
 	bool cont = true;
-	while (cont && i < count) {
-		pair = &evidence->items[i++];
+	while (cont && evidence != NULL) {
+
+		// Check the current evidence item and call back if the right prefix
+		// after parsing the pair if not done so already.
+		pair = &evidence->items[index++];
 		if ((pair->prefix & prefixes) == pair->prefix) {
 			if (pair->parsedValue == NULL) {
 				parsePair(pair);
@@ -88,10 +102,36 @@ static uint32_t evidenceIterate(
 			cont = callback(state, pair);
 			iterations++;
 		}
+
+		// Check if the next evidence array needs to be moved to.
+		if (index >= evidence->count) {
+			evidence = evidence->next;
+			index = 0;
+		}
 	}
 	return iterations;
 }
 
+/**
+ * If the header name and pair key match then stop iterating having set the 
+ * found pair, otherwise return false.
+ */
+static bool findHeaderEvidenceCallback(
+	void* state,
+	EvidenceKeyValuePair* pair) {
+	evidenceFindState* findState = (evidenceFindState*)state;
+	if (findState->header == pair->header || (
+		findState->header->nameLength == pair->item.keyLength &&
+		StringCompareLength(
+			findState->header->name,
+			pair->item.key,
+			pair->item.keyLength) == 0)) {
+		findState->pair = pair;
+		return false;
+	}
+	return true;
+}
+
 /**
  * Finds the evidence pair that matches the header. Returns null if a pair does
  * not exist.
@@ -100,39 +140,20 @@ static EvidenceKeyValuePair* findHeaderEvidence(
 	EvidenceKeyValuePairArray* evidence,
 	int prefixes,
 	Header* header) {
-	EvidenceKeyValuePair* pair;
-
-	// For each of the evidence pairs available.
-	for (uint32_t i = 0; i < evidence->count; i++) {
-		pair = &evidence->items[i];
-
-		// Check that the prefix is one that is being considered.
-		if ((pair->prefix & prefixes) == pair->prefix) {
-
-			// If the header has been assigned to the pair check to see if this
-			// one is a match.
-			if (pair->header == NULL) {
-				setPairHeader(pair, header);
-			}
-
-			// If the pair's header and the required header are the same.
-			if (pair->header == header) {
-
-				// Ensure the parsed value is populated before returning.
-				if (pair->parsedValue == NULL) {
-					parsePair(pair);
-				}
-				return pair;
-			}
-		}
-	}
-	return NULL;
+	evidenceFindState state = { header, NULL };
+	evidenceIterate(evidence, prefixes, &state, findHeaderEvidenceCallback);
+	return state.pair;
 }
 
 // Safe-copies the pair parsed value to the buffer checking that there are
 // sufficient bytes remaining in the buffer for the parsed value.
-static void addPairValueToBuffer(StringBuilder* builder, EvidenceKeyValuePair* pair) {
-	StringBuilderAddChars(builder, (char*)pair->parsedValue, pair->parsedLength);
+static void addPairValueToBuffer(
+	StringBuilder* builder, 
+	EvidenceKeyValuePair* pair) {
+	StringBuilderAddChars(
+		builder, 
+		(char*)pair->parsedValue, 
+		pair->parsedLength);
 }
 
 // For the header finds the corresponding evidence in the array of evidence. If
@@ -166,8 +187,8 @@ static bool addHeaderValueToBuilder(
 	// current character in the buffer.
 	addPairValueToBuffer(builder, pair);
     
-    // return false if we have overfilled the buffer
-    return !builder->full;
+    // Return false if we have overfilled the buffer.
+    return builder->full == false;
 }
 
 // Assembles a pseudo header in the buffer. If this can not be achieved returns 
@@ -180,11 +201,13 @@ static bool processPseudoHeader(
 	Header* header,
 	StringBuilder* builder,
 	void* state,
-	fiftyoneDegreesEvidenceIterateForHeadersMethod callback) {
+	fiftyoneDegreesEvidenceIterateMethod callback) {
+	EvidenceKeyValuePair pair;
 
 	// For each of the headers that form the pseudo header.
 	for (uint32_t i = 0; i < header->segmentHeaders->count; i++) {
-        //if this is a subsequent segment - we prepend the separator
+        
+		// if this is a subsequent segment - we prepend the separator
         bool prependSeparator = i > 0;
 
 		// Add the header evidence that forms the segment if available updating
@@ -207,9 +230,17 @@ static bool processPseudoHeader(
 	// character.
 	StringBuilderComplete(builder);
 
-	// A full header has been formed so call the callback with the buffer and
-	// the number of characters populated.
-	return callback(state, header, builder->ptr, builder->added);
+	// A full header has been formed so call the callback with an evidence pair 
+	// containing the parsed value.
+	pair.item.key = NULL;
+	pair.item.keyLength = 0;
+	pair.header = header;
+	pair.item.value = builder->ptr;
+	pair.item.valueLength = builder->added;
+	pair.parsedValue = builder->ptr;
+	pair.parsedLength = builder->added;
+	pair.prefix = 0;
+	return callback(state, &pair);
 }
 
 // Finds the header in the evidence, and if available calls the callback. 
@@ -220,7 +251,7 @@ static bool processHeader(
 	int prefixes,
 	Header* header,
 	void* state,
-	fiftyoneDegreesEvidenceIterateForHeadersMethod callback) {
+	fiftyoneDegreesEvidenceIterateMethod callback) {
 
 	// Get the evidence that corresponds to the header. If it doesn't exist
 	// then there is no evidence for the header and a call back will not be
@@ -233,27 +264,26 @@ static bool processHeader(
 		return true;
 	}
 
-	// A full header has been formed so call the callback with the buffer and
-	// the number of characters populated.
-	return callback(
-		state, 
-		header, 
-		(const char*)pair->parsedValue, 
-		pair->parsedLength);
+	// A full header has been formed so call the callback with the pair.
+	return callback(state, pair);
 }
 
 fiftyoneDegreesEvidenceKeyValuePairArray*
 fiftyoneDegreesEvidenceCreate(uint32_t capacity) {
-	EvidenceKeyValuePairArray *evidence;
+	fiftyoneDegreesEvidenceKeyValuePairArray *evidence;
 	uint32_t i;
 	FIFTYONE_DEGREES_ARRAY_CREATE(EvidenceKeyValuePair, evidence, capacity);
 	if (evidence != NULL) {
+		evidence->next = NULL;
+		evidence->prev = NULL;
 		for (i = 0; i < evidence->capacity; i++) {
-			evidence->items[i].field = NULL;
-			evidence->items[i].fieldLength = 0;
+			evidence->items[i].item.key = NULL;
+			evidence->items[i].item.keyLength = 0;
+			evidence->items[i].item.value = NULL;
+			evidence->items[i].item.valueLength = 0;
 			evidence->items[i].header = NULL;
-			evidence->items[i].originalValue = NULL;
 			evidence->items[i].parsedValue = NULL;
+			evidence->items[i].parsedLength = 0;
 			evidence->items[i].prefix = FIFTYONE_DEGREES_EVIDENCE_IGNORE;
 		}
 	}
@@ -262,27 +292,58 @@ fiftyoneDegreesEvidenceCreate(uint32_t capacity) {
 
 void fiftyoneDegreesEvidenceFree(
 	fiftyoneDegreesEvidenceKeyValuePairArray *evidence) {
-	Free(evidence);
+    if (evidence == NULL) {
+        return;
+    }
+	EvidenceKeyValuePairArray* current = evidence;
+	while (current->next != NULL) {
+		current = current->next;
+	}
+	while (current != NULL) {
+		evidence = current->prev;
+		Free(current);
+		current = evidence;
+	}
 }
 
-fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddString(
+fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddPair(
 	fiftyoneDegreesEvidenceKeyValuePairArray *evidence,
 	fiftyoneDegreesEvidencePrefix prefix,
-	const char *field,
-	const char *originalValue) {
+	fiftyoneDegreesKeyValuePair value) {
 	EvidenceKeyValuePair *pair = NULL;
-	if (evidence->count < evidence->capacity) {
-		pair = &evidence->items[evidence->count++];
-		pair->prefix = prefix;
-		pair->field = field;
-		pair->fieldLength = strlen(field);
-		pair->originalValue = (void*)originalValue;
-		pair->parsedValue = NULL;
-		pair->header = NULL;
+	while (pair == NULL) {
+		if (evidence->count < evidence->capacity) {
+			// Use the next item in the allocated array.
+			pair = &evidence->items[evidence->count++];
+			pair->prefix = prefix;
+			pair->item = value;
+			pair->parsedValue = NULL;
+			pair->header = NULL;
+		}
+		else {
+			// If there is insufficient capacity in the evidence array then add
+			// a new array.
+			if (evidence->next == NULL) {
+				evidence->next = EvidenceCreate(
+					evidence->capacity == 0 ? 1 : evidence->capacity);
+				evidence->next->prev = evidence;
+			}
+			// Move to the next evidence array.
+			evidence = evidence->next;
+		}
 	}
 	return pair;
 }
 
+fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddString(
+	fiftyoneDegreesEvidenceKeyValuePairArray* evidence,
+	fiftyoneDegreesEvidencePrefix prefix,
+	const char* key,
+	const char* value) {
+	KeyValuePair pair = { key, strlen(key), value, strlen(value) };
+	return EvidenceAddPair(evidence, prefix, pair);
+}
+
 uint32_t fiftyoneDegreesEvidenceIterate(
 	fiftyoneDegreesEvidenceKeyValuePairArray *evidence,
 	int prefixes,
@@ -312,7 +373,7 @@ fiftyoneDegreesEvidencePrefixMap* fiftyoneDegreesEvidenceMapPrefix(
 	return result;
 }
 
-EXTERNAL const char* fiftyoneDegreesEvidencePrefixString(
+const char* fiftyoneDegreesEvidencePrefixString(
 	fiftyoneDegreesEvidencePrefix prefix) {
 	uint32_t i;
 	EvidencePrefixMap* map;
@@ -334,7 +395,7 @@ bool fiftyoneDegreesEvidenceIterateForHeaders(
 	char* const buffer,
 	size_t const length,
 	void* state,
-	fiftyoneDegreesEvidenceIterateForHeadersMethod callback) {
+	fiftyoneDegreesEvidenceIterateMethod callback) {
 	Header* header;
 	StringBuilder builder = { buffer, length };
 
diff --git a/evidence.h b/evidence.h
index 70eda75d..eecdd772 100644
--- a/evidence.h
+++ b/evidence.h
@@ -124,6 +124,7 @@
 #include "string.h"
 #include "array.h"
 #include "common.h"
+#include "pair.h"
 #include "headers.h"
 
 /**
@@ -159,18 +160,35 @@ typedef struct fiftyone_degrees_evidence_prefix_map_t {
  */
 typedef struct fiftyone_degrees_evidence_key_value_pair_t {
 	fiftyoneDegreesEvidencePrefix prefix; /**< e.g. #FIFTYONE_DEGREES_EVIDENCE_HTTP_HEADER_STRING */
-	const char *field; /**< e.g. User-Agent or ScreenPixelsWidth */
-	size_t fieldLength; /**< length of field */
-	const void *originalValue; /**< original unparsed value */
+	fiftyoneDegreesKeyValuePair item; /**< the field key and original value */
 	const void *parsedValue; /**< parsed value which may not be a string */
 	size_t parsedLength; /**< length of parsedValue string */
 	fiftyoneDegreesHeader* header; /**< Unique header in the data set, or 
 								   null if not related to a header */
 } fiftyoneDegreesEvidenceKeyValuePair;
 
+/**
+ * Forward declaration of the array so that it can point to an instance of the 
+ * same type.
+ */
+typedef struct fiftyone_degrees_array_fiftyoneDegreesEvidenceKeyValuePair_t 
+	fiftyoneDegreesEvidenceKeyValuePairArray;
+
+/**
+ * Pointers to the next and previous array of evidence key value pairs or 
+ * NULL if not present.
+ */
+#define FIFTYONE_DEGREES_ARRAY_EVIDENCE_MEMBER \
+	fiftyoneDegreesEvidenceKeyValuePairArray *next; \
+	fiftyoneDegreesEvidenceKeyValuePairArray *prev;
+
+/**
+ * Array of evidence key value pairs and a pointer to the next array if present
+ * or NULL of not present.
+ */
 FIFTYONE_DEGREES_ARRAY_TYPE(
 	fiftyoneDegreesEvidenceKeyValuePair,
-	)
+	FIFTYONE_DEGREES_ARRAY_EVIDENCE_MEMBER)
 
 /**
  * Callback method used to iterate evidence key value pairs.
@@ -182,31 +200,17 @@ typedef bool(*fiftyoneDegreesEvidenceIterateMethod)(
 	void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair);
 
-/**
- * Callback method used to iterate evidence key value pairs for an array of 
- * headers.
- * @param state pointer provided to the iterator
- * @param header that the value is related to
- * @param value from the evidence for the header
- * @param length of the value
- * @return true if the iteration should continue otherwise false
- */
-typedef bool(*fiftyoneDegreesEvidenceIterateForHeadersMethod)(
-	void* state,
-	fiftyoneDegreesHeader* header,
-	const char* value,
-	size_t length);
-
 /**
  * Creates a new evidence array with the capacity requested.
  * @param capacity maximum number of evidence items
  * @return pointer to the newly created array
  */
 EXTERNAL fiftyoneDegreesEvidenceKeyValuePairArray* 
-fiftyoneDegreesEvidenceCreate(uint32_t capacity);
+	fiftyoneDegreesEvidenceCreate(uint32_t capacity);
 
 /**
- * Frees the memory used by an evidence array.
+ * Frees the memory used by an evidence array and any other arrays pointed to
+ * by the instance passed via the next member.
  * @param evidence pointer to the array to be freed
  */
 EXTERNAL void fiftyoneDegreesEvidenceFree(
@@ -216,16 +220,37 @@ EXTERNAL void fiftyoneDegreesEvidenceFree(
  * Adds a new entry to the evidence. The memory associated with the 
  * field and original value parameters must not be freed until after the 
  * evidence collection has been freed. This method will NOT copy the values.
+ * If there is insufficient capacity in the evidence array then another array
+ * will be created and will be pointed to by the next member of the evidence 
+ * array passed.
  * @param evidence pointer to the evidence array to add the entry to
  * @param prefix enum indicating the category the entry belongs to
- * @param field used as the key for the entry within its prefix
- * @param originalValue the value to be parsed
+ * @param key string with null terminator
+ * @param value string with null terminator
+ * @returns the new evidence key value pair instance
  */
 EXTERNAL fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddString(
 	fiftyoneDegreesEvidenceKeyValuePairArray *evidence,
 	fiftyoneDegreesEvidencePrefix prefix,
-	const char *field,
-	const char *originalValue);
+	const char *key,
+	const char *value);
+
+/**
+ * Adds a new entry to the evidence. The memory associated with the
+ * field and original value parameters must not be freed until after the
+ * evidence collection has been freed. This method will NOT copy the values.
+ * If there is insufficient capacity in the evidence array then another array
+ * will be created and will be pointed to by the next member of the evidence
+ * array passed.
+ * @param evidence pointer to the evidence array to add the entry to
+ * @param prefix enum indicating the category the entry belongs to
+ * @param pair used as the key and value for the new entry
+ * @returns the new evidence key value pair instance
+ */
+EXTERNAL fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddPair(
+	fiftyoneDegreesEvidenceKeyValuePairArray* evidence,
+	fiftyoneDegreesEvidencePrefix prefix,
+	fiftyoneDegreesKeyValuePair pair);
 
 /**
  * Determines the evidence map prefix from the key.
@@ -260,22 +285,6 @@ EXTERNAL uint32_t fiftyoneDegreesEvidenceIterate(
 	void *state,
 	fiftyoneDegreesEvidenceIterateMethod callback);
 
-
-/**
- * First checks if provided prefix+field are not already part of the 
- * evidence array with the same parameters.
- * If not calls fiftyoneDegreesEvidenceAddString.
- * @param evidence pointer to the evidence array to add the entry to
- * @param prefix enum indicating the category the entry belongs to
- * @param field used as the key for the entry within its prefix
- * @param originalValue the value to be parsed
- */
-EXTERNAL fiftyoneDegreesEvidenceKeyValuePair* fiftyoneDegreesEvidenceAddStringUnique(
-    fiftyoneDegreesEvidenceKeyValuePairArray *evidence,
-    fiftyoneDegreesEvidencePrefix prefix,
-    const char *field,
-    const char *originalValue);
-
 /**
  * Iterates over the headers assembling the evidence values, considering the 
  * prefixes, in the buffer if available. The call back method is called for 
@@ -300,7 +309,7 @@ EXTERNAL bool fiftyoneDegreesEvidenceIterateForHeaders(
 	char* const buffer,
 	size_t const length,
 	void* state,
-	fiftyoneDegreesEvidenceIterateForHeadersMethod callback);
+	fiftyoneDegreesEvidenceIterateMethod callback);
 
 /**
  * @}
diff --git a/fiftyone.h b/fiftyone.h
index 92ec4a16..cf120ce5 100644
--- a/fiftyone.h
+++ b/fiftyone.h
@@ -287,6 +287,7 @@ MAP_TYPE(KeyValuePairArray)
 #define EvidenceCreate fiftyoneDegreesEvidenceCreate /**< Synonym for #fiftyoneDegreesEvidenceCreate function. */
 #define EvidenceMapPrefix fiftyoneDegreesEvidenceMapPrefix /**< Synonym for #fiftyoneDegreesEvidenceMapPrefix function. */
 #define EvidencePrefixString fiftyoneDegreesEvidencePrefixString /**< Synonym for #fiftyoneDegreesEvidencePrefixString function. */
+#define EvidenceAddPair fiftyoneDegreesEvidenceAddPair /**< Synonym for #fiftyoneDegreesEvidenceAddPair function. */
 #define EvidenceAddString fiftyoneDegreesEvidenceAddString /**< Synonym for #fiftyoneDegreesEvidenceAddString function. */
 #define PropertiesGetRequiredPropertyIndexFromName fiftyoneDegreesPropertiesGetRequiredPropertyIndexFromName /**< Synonym for #fiftyoneDegreesPropertiesGetRequiredPropertyIndexFromName function. */
 #define PropertiesGetNameFromRequiredIndex fiftyoneDegreesPropertiesGetNameFromRequiredIndex /**< Synonym for #fiftyoneDegreesPropertiesGetNameFromRequiredIndex function. */
@@ -358,6 +359,7 @@ MAP_TYPE(KeyValuePairArray)
 #define StringBuilderAddChars fiftyoneDegreesStringBuilderAddChars /**< Synonym for fiftyoneDegreesStringBuilderAddChars */
 #define StringBuilderComplete fiftyoneDegreesStringBuilderComplete /**< Synonym for fiftyoneDegreesStringBuilderComplete */
 #define EvidenceIterateMethod fiftyoneDegreesEvidenceIterateMethod /**< Synonym for fiftyoneDegreesEvidenceIterateMethod */
+#define OverrideHasValueForRequiredPropertyIndex fiftyoneDegreesOverrideHasValueForRequiredPropertyIndex /**< Synonym for fiftyoneDegreesOverrideHasValueForRequiredPropertyIndex */
 
 /* <-- only one asterisk to avoid inclusion in documentation
  * Shortened macros.
diff --git a/headers.c b/headers.c
index a02bfe70..dbaafc80 100644
--- a/headers.c
+++ b/headers.c
@@ -77,7 +77,7 @@ static void initHeaders(Headers* headers) {
 		h->index = i;
 		h->headerId = 0;
 		h->isDataSet = false;
-		h->length = 0;
+		h->nameLength = 0;
 		h->name = NULL;
 		h->pseudoHeaders = NULL;
 		h->segmentHeaders = NULL;
@@ -181,7 +181,7 @@ static bool setHeaderName(
 		return false;
 	}
 	name[length] = '\0';
-	header->length = length;
+	header->nameLength = length;
 	return true;
 }
 
@@ -246,7 +246,7 @@ static Header* getHeader(Headers* headers, const char* name, size_t length) {
 	Header* item;
 	for (uint32_t i = 0; i < headers->count; i++) {
 		item = &headers->items[i];
-		if (item->length == length &&
+		if (item->nameLength == length &&
 			StringCompareLength(name, item->name, length) == 0) {
 			return item;
 		}
@@ -337,7 +337,7 @@ static Header* copyHeader(
 	if (setHeaderName(
 		copied, 
 		source->name, 
-		source->length, 
+		source->nameLength, 
 		exception) == false) {
 		return NULL;
 	}
@@ -401,7 +401,7 @@ static bool addHeadersFromHeader(
 	uint32_t start = 0;
 	uint32_t end = 0;
     bool separatorEncountered = false;
-	for (;end < pseudoHeader->length; end++) {
+	for (;end < pseudoHeader->nameLength; end++) {
 
 		// If a header has been found then either get the existing header with
 		// this name, or add a new header.
@@ -583,7 +583,7 @@ int fiftyoneDegreesHeaderGetIndex(
 	// Perform a case insensitive compare of the remaining characters.
 	for (i = 0; i < headers->count; i++) {
 		header = &headers->items[i];
-		if (header->length == length &&
+		if (header->nameLength == length &&
 			StringCompareLength(
 				httpHeaderName, 
 				header->name,
diff --git a/headers.h b/headers.h
index fe8bacd3..c3e22220 100644
--- a/headers.h
+++ b/headers.h
@@ -138,7 +138,7 @@ struct fiftyone_degrees_header_t {
 	uint32_t index; /**< Index of the header in the array of all headers */
 	const char* name; /**< Name of the header or pseudo header field as a
 					       null terminated string */
-	size_t length; /**< Length of the name string excluding the terminating 
+	size_t nameLength; /**< Length of the name string excluding the terminating 
 						null */
 	fiftyoneDegreesHeaderID headerId; /**< Unique id in the data set for this 
 									  full header */
@@ -183,13 +183,6 @@ typedef long(*fiftyoneDegreesHeadersGetMethod)(
 	uint32_t index, 
 	fiftyoneDegreesCollectionItem *nameItem);
 
-/**
- * Check if a header is a pseudo header.
- * @param headerName name of the header
- * @return whether a header is a pseudo header.
- */
-EXTERNAL bool fiftyoneDegreesHeadersIsPseudo(const char *headerName);
-
 /**
  * Creates a new headers instance configured with the unique HTTP names needed
  * from evidence. If the useUpperPrefixedHeaders flag is true then checks for 
diff --git a/overrides.c b/overrides.c
index 75559292..ccef8e51 100644
--- a/overrides.c
+++ b/overrides.c
@@ -57,7 +57,8 @@ static void collectionRelease(Item *item) {
  * characters. Take 1 from the t to compare length.
  */
 #define IS_HEADER_MATCH(t,p) \
-	(StringCompareLength(skipPrefix(true, (char*)pair->field), t, sizeof(t)) == 0)
+	(StringCompareLength(\
+	skipPrefix(true, (char*)pair->item.key), t, sizeof(t)) == 0)
 
 static const Collection dummyCollection = { 
 	NULL, 
@@ -183,7 +184,7 @@ static bool addOverrideToResults(void *state, EvidenceKeyValuePair *pair) {
 	// Find the required property index, if any for the field.
 	int requiredPropertyIndex = getRequiredPropertyIndexFromName(
 		add->properties,
-		pair->field);
+		pair->item.key);
 
 	return fiftyoneDegreesOverridesAdd(
 		add->values,
diff --git a/pair.h b/pair.h
index bb6a4c55..c66c4baa 100644
--- a/pair.h
+++ b/pair.h
@@ -27,10 +27,10 @@
 #include <stddef.h>
 
 typedef struct fiftyone_degrees_key_value_pair_t {
-	char* key;
-	size_t keyLength;
-	char* value;
-	size_t valueLength;
+	const char* key; /**< pointer to the key string */
+	size_t keyLength; /**< number of characters in key */
+	const char* value; /**< pointer to the value string */
+	size_t valueLength; /**< number of characters in value */
 } fiftyoneDegreesKeyValuePair;
 
 FIFTYONE_DEGREES_ARRAY_TYPE(fiftyoneDegreesKeyValuePair, )
diff --git a/tests/EvidenceTests.cpp b/tests/EvidenceTests.cpp
index 18b89857..f1fa9697 100644
--- a/tests/EvidenceTests.cpp
+++ b/tests/EvidenceTests.cpp
@@ -30,10 +30,10 @@ void assertStringHeaderAdded(
 	const char *expectedValue) {
 	EXPECT_EQ((int)pair->prefix, (int)FIFTYONE_DEGREES_EVIDENCE_HTTP_HEADER_STRING) <<
 		L"Expected 'header' prefix.";
-	EXPECT_STREQ(pair->field, expectedField) <<
-		L"Expected name '" << expectedField << "' not '" << pair->field << "'";
-	EXPECT_TRUE(strcmp((const char*)pair->originalValue, expectedValue) == 0) <<
-		L"Expected value '" << expectedValue << "' not '" << pair->originalValue << "'";
+	EXPECT_STREQ(pair->item.key, expectedField) <<
+		L"Expected name '" << expectedField << "' not '" << pair->item.key << "'";
+	EXPECT_TRUE(strcmp((const char*)pair->item.value, expectedValue) == 0) <<
+		L"Expected value '" << expectedValue << "' not '" << pair->item.value << "'";
 }
 
 TEST_F(Evidence, Get_PrefixString) {
@@ -99,9 +99,9 @@ TEST_F(Evidence, Add_MultipleStrings)
 #endif
 bool onMatchIterateString(void *state, fiftyoneDegreesEvidenceKeyValuePair *pair)
 {
-	if (strcmp((const char*)pair->field, "some-header-name") == 0) {
-		EXPECT_TRUE(strcmp((const char*)pair->originalValue, (const char*)pair->parsedValue) == 0) <<
-			L"Expected parsed value to be '" << (const char*)pair->originalValue << "' not '" <<
+	if (strcmp((const char*)pair->item.key, "some-header-name") == 0) {
+		EXPECT_TRUE(strcmp((const char*)pair->item.value, (const char*)pair->parsedValue) == 0) <<
+			L"Expected parsed value to be '" << (const char*)pair->item.value << "' not '" <<
 			(const char*)pair->parsedValue << "'";
 	}
 	return true;
@@ -203,9 +203,9 @@ TEST_F(Evidence, Iterate_String_without_pseudo_evidence) {
 		"Number of evidence should be 1\n";
 }
 
-bool callback1(void* state, fiftyoneDegreesHeader*, const char* value, size_t) {
+bool callback1(void* state, fiftyoneDegreesEvidenceKeyValuePair* pair) {
     std::vector<std::string> *results = (std::vector<std::string> *) state;
-    results->push_back(value);
+    results->push_back(pair->item.value);
     return true;
 }
 
@@ -361,9 +361,9 @@ TEST_F(Evidence, IterateForHeaders_ConstructPseudoHeader_Missing_or_Empty) {
     EXPECT_EQ(results[1], "\x1FGreen\x1F""Apple");
 }
 
-bool callback2(void* state, fiftyoneDegreesHeader* , const char* value, size_t ) {
+bool callback2(void* state, fiftyoneDegreesEvidenceKeyValuePair *pair) {
     std::vector<std::string> *results = (std::vector<std::string> *) state;
-    results->push_back(value);
+    results->push_back(pair->item.value);
     return results->size() <= 1; // on the second header we signal early exit by returning false
 }
 
@@ -388,7 +388,7 @@ TEST_F(Evidence, IterateForHeaders_CallbackSignalsEarlyExit) {
     EXPECT_EQ(results[1], "Big\x1FGreen");
 }
 
-bool callback_false(void* , fiftyoneDegreesHeader* , const char* , size_t ) {
+bool callback_false(void*, fiftyoneDegreesEvidenceKeyValuePair*) {
     return false;
 }
 
@@ -438,4 +438,7 @@ TEST_F(Evidence, IterateForHeaders_SmallBuffer) {
     fiftyoneDegreesFree(buf);
 }
 
-
+TEST_F(Evidence, freeNullEvidence) {
+    fiftyoneDegreesEvidenceKeyValuePairArray *evidence2 = NULL;
+    EvidenceFree(evidence2);
+}
diff --git a/tests/EvidenceWithHeadersTests_MultipleHeaders.cpp b/tests/EvidenceWithHeadersTests_MultipleHeaders.cpp
index 77233a9b..97c220b2 100644
--- a/tests/EvidenceWithHeadersTests_MultipleHeaders.cpp
+++ b/tests/EvidenceWithHeadersTests_MultipleHeaders.cpp
@@ -114,8 +114,8 @@ TEST_F(EvidenceWithHeadersTest_MultipleHeaders, Intersection_mh_se_sm) {
 		evidenceHeaderIntersection_mh_se_sm);
 
 	ASSERT_EQ(1, result);
-	ASSERT_STREQ("Black", intersection_mh_se_sm[0].field);
-	ASSERT_STREQ("Value", (char*)intersection_mh_se_sm[0].originalValue);
+	ASSERT_STREQ("Black", intersection_mh_se_sm[0].item.key);
+	ASSERT_STREQ("Value", (char*)intersection_mh_se_sm[0].item.value);
 }
 
 
@@ -160,10 +160,10 @@ TEST_F(EvidenceWithHeadersTest_MultipleHeaders, Intersection_mh_me_mm) {
 		evidenceHeaderIntersection_mh_me_mm);
 
 	ASSERT_EQ(2, result);
-	EXPECT_STREQ("Black", intersection_mh_me_mm[0].field);
-	EXPECT_STREQ("Value", (char*)intersection_mh_me_mm[0].originalValue);
-	EXPECT_STREQ("Red", intersection_mh_me_mm[1].field);
-	EXPECT_STREQ("Value2", (char*)intersection_mh_me_mm[1].originalValue);
+	EXPECT_STREQ("Black", intersection_mh_me_mm[0].item.key);
+	EXPECT_STREQ("Value", (char*)intersection_mh_me_mm[0].item.value);
+	EXPECT_STREQ("Red", intersection_mh_me_mm[1].item.key);
+	EXPECT_STREQ("Value2", (char*)intersection_mh_me_mm[1].item.value);
 }
 
 //------------------------------------------------------------------
@@ -177,8 +177,8 @@ bool evidenceHeaderIntersection_mh_me_nm(void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair) {
 	if (fiftyoneDegreesHeaderGetIndex(
 		(fiftyoneDegreesHeaders*)state,
-		pair->field,
-		strlen(pair->field)) >= 0) {
+		pair->item.key,
+		pair->item.keyLength) >= 0) {
 		intersection_mh_me_nm[intersection_mh_me_nm_count] = *pair;
 		intersection_mh_me_nm_count++;
 	}
diff --git a/tests/EvidenceWithHeadersTests_NoHeaders.cpp b/tests/EvidenceWithHeadersTests_NoHeaders.cpp
index 3f8e16bc..44729763 100644
--- a/tests/EvidenceWithHeadersTests_NoHeaders.cpp
+++ b/tests/EvidenceWithHeadersTests_NoHeaders.cpp
@@ -81,8 +81,8 @@ bool evidenceHeaderIntersection_nh_se_nm(void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair) {
 	if (fiftyoneDegreesHeaderGetIndex(
 		(fiftyoneDegreesHeaders*)state,
-		pair->field,
-		strlen(pair->field)) >= 0) {
+		pair->item.key,
+		pair->item.keyLength) >= 0) {
 		intersection_nh_se_nm[intersection_nh_se_nm_count] = *pair;
 		intersection_nh_se_nm_count++;
 	}
@@ -118,8 +118,8 @@ bool evidenceHeaderIntersection_nh_me_mm(void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair) {
 	if (fiftyoneDegreesHeaderGetIndex(
 		(fiftyoneDegreesHeaders*)state,
-		pair->field,
-		strlen(pair->field)) >= 0) {
+		pair->item.key,
+		pair->item.keyLength) >= 0) {
 		intersection_nh_me_nm[intersection_multiple_nh_me_mm_count] = *pair;
 		intersection_multiple_nh_me_mm_count++;
 	}
diff --git a/tests/EvidenceWithHeadersTests_SingleHeader.cpp b/tests/EvidenceWithHeadersTests_SingleHeader.cpp
index f34376ae..a706d02d 100644
--- a/tests/EvidenceWithHeadersTests_SingleHeader.cpp
+++ b/tests/EvidenceWithHeadersTests_SingleHeader.cpp
@@ -111,8 +111,8 @@ TEST_F(EvidenceWithHeadersTest_SingleHeader, Intersection_sh_se_sm) {
 		evidenceHeaderIntersection_sh_se_sm);
 
 	ASSERT_EQ(1, result);
-	ASSERT_STREQ("Red", intersection_sh_se_sm[0].field);
-	ASSERT_STREQ("Value", (char*)intersection_sh_se_sm[0].originalValue);
+	ASSERT_STREQ("Red", intersection_sh_se_sm[0].item.key);
+	ASSERT_STREQ("Value", (char*)intersection_sh_se_sm[0].item.value);
 }
 
 
@@ -130,8 +130,8 @@ bool evidenceHeaderIntersection_sh_me_mm(void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair) {
 	if (fiftyoneDegreesHeaderGetIndex(
 		(fiftyoneDegreesHeaders*)state,
-		pair->field,
-		strlen(pair->field)) >= 0) {
+		pair->item.key,
+		pair->item.keyLength) >= 0) {
 		intersection_sh_me_sm[intersection_multiple_sh_me_mm_count] = *pair;
 		intersection_multiple_sh_me_mm_count++;
 	}
@@ -162,8 +162,8 @@ TEST_F(EvidenceWithHeadersTest_SingleHeader, Intersection_sh_me_sm) {
 
 	ASSERT_EQ(2, result);
 	ASSERT_EQ(1, intersection_multiple_sh_me_mm_count);
-	EXPECT_STREQ("Red", intersection_sh_me_sm[0].field);
-	EXPECT_STREQ("Value2", (char*)intersection_sh_me_sm[0].originalValue);
+	EXPECT_STREQ("Red", intersection_sh_me_sm[0].item.key);
+	EXPECT_STREQ("Value2", (char*)intersection_sh_me_sm[0].item.value);
 }
 
 //------------------------------------------------------------------
@@ -181,8 +181,8 @@ bool evidenceHeaderIntersection_sh_me_nm(void *state,
 	fiftyoneDegreesEvidenceKeyValuePair *pair) {
 	if (fiftyoneDegreesHeaderGetIndex(
 		(fiftyoneDegreesHeaders*)state,
-		pair->field,
-		strlen(pair->field)) >= 0) {
+		pair->item.key,
+		pair->item.keyLength) >= 0) {
 		intersection_sh_me_nm[intersection_sh_me_nm_count] = *pair;
 		intersection_sh_me_nm_count++;
 	}
diff --git a/tests/HeadersTests.cpp b/tests/HeadersTests.cpp
index 41644c85..7601bfba 100644
--- a/tests/HeadersTests.cpp
+++ b/tests/HeadersTests.cpp
@@ -371,8 +371,8 @@ TEST_F(HeadersTests, PseudoHeadersPositive) {
 
 	EXPECT_STREQ("header1\x1Fheader2", headers->items[3].name);
 	EXPECT_EQ(2, headers->items[3].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[0]->length);
-	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[1]->length);
+	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[0]->nameLength);
+	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[1]->nameLength);
 	EXPECT_EQ(0, StringCompareLength(
 		"header1", 
 		headers->items[3].segmentHeaders->items[0]->name,
@@ -387,8 +387,8 @@ TEST_F(HeadersTests, PseudoHeadersPositive) {
 
 	EXPECT_STREQ("header2\x1Fheader3", headers->items[4].name);
 	EXPECT_EQ(2, headers->items[4].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[0]->length);
-	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[1]->length);
+	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[0]->nameLength);
+	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[1]->nameLength);
 	EXPECT_EQ(0, StringCompareLength(
 		"header2",
 		headers->items[4].segmentHeaders->items[0]->name,
@@ -403,9 +403,9 @@ TEST_F(HeadersTests, PseudoHeadersPositive) {
 
 	EXPECT_STREQ("header1\x1Fheader2\x1Fheader3", headers->items[5].name);
 	EXPECT_EQ(3, headers->items[5].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[0]->length);
-	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[1]->length);
-	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[2]->length);
+	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[0]->nameLength);
+	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[1]->nameLength);
+	EXPECT_EQ(7, headers->items[5].segmentHeaders->items[2]->nameLength);
 	
     EXPECT_EQ(0, StringCompareLength(
 		"header1",
@@ -445,11 +445,11 @@ TEST_F(HeadersTests, PseudoHeadersMissing) {
 	EXPECT_STREQ("header1\x1Fheader2", headers->items[0].name);
 	EXPECT_EQ(true, headers->items[0].isDataSet);
 	EXPECT_EQ(2, headers->items[0].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[0].segmentHeaders->items[0]->length);
+	EXPECT_EQ(7, headers->items[0].segmentHeaders->items[0]->nameLength);
     EXPECT_EQ(1, headers->items[0].segmentHeaders->items[0]->pseudoHeaders->count);
     EXPECT_EQ(&headers->items[0], headers->items[0].segmentHeaders->items[0]->pseudoHeaders->items[0]);
     
-	EXPECT_EQ(7, headers->items[0].segmentHeaders->items[1]->length);
+	EXPECT_EQ(7, headers->items[0].segmentHeaders->items[1]->nameLength);
     EXPECT_EQ(1, headers->items[0].segmentHeaders->items[1]->pseudoHeaders->count);
     EXPECT_EQ(&headers->items[0], headers->items[0].segmentHeaders->items[1]->pseudoHeaders->items[0]);
     
@@ -510,7 +510,7 @@ TEST_F(HeadersTests, PseudoHeadersSpecialCases) {
 
 	EXPECT_STREQ("\x1Fheader1", headers->items[2].name);
 	EXPECT_EQ(1, headers->items[2].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[2].segmentHeaders->items[0]->length);
+	EXPECT_EQ(7, headers->items[2].segmentHeaders->items[0]->nameLength);
 	EXPECT_EQ(0, StringCompareLength(
 		"header1",
 		headers->items[2].segmentHeaders->items[0]->name,
@@ -522,7 +522,7 @@ TEST_F(HeadersTests, PseudoHeadersSpecialCases) {
 
 	EXPECT_STREQ("header1\x1F", headers->items[3].name);
 	EXPECT_EQ(1, headers->items[3].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[0]->length);
+	EXPECT_EQ(7, headers->items[3].segmentHeaders->items[0]->nameLength);
 	EXPECT_EQ(0, StringCompareLength(
 		"header1",
 		headers->items[3].segmentHeaders->items[0]->name,
@@ -534,8 +534,8 @@ TEST_F(HeadersTests, PseudoHeadersSpecialCases) {
 
 	EXPECT_STREQ("header1\x1F\x1Fheader2", headers->items[4].name);
 	EXPECT_EQ(2, headers->items[4].segmentHeaders->count);
-	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[0]->length);
-	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[1]->length);
+	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[0]->nameLength);
+	EXPECT_EQ(7, headers->items[4].segmentHeaders->items[1]->nameLength);
 	EXPECT_EQ(0, StringCompareLength(
 		"header1",
 		headers->items[4].segmentHeaders->items[0]->name,
diff --git a/yamlfile.c b/yamlfile.c
index 0fc5bae0..cfae8be9 100644
--- a/yamlfile.c
+++ b/yamlfile.c
@@ -85,15 +85,15 @@ static char* readNext(FileState* fileState) {
 // Sets the current and end pointers to the current key.
 static void setCurrentKey(PairState* state) {
 	KeyValuePair* current = state->pairs + state->index;
-	state->current = current->key;
-	state->end = current->key + current->keyLength - 1;
+	state->current = (char*)current->key;
+	state->end = (char*)(current->key + current->keyLength - 1);
 }
 
 // Sets the current and end pointers to the current value.
 static void setCurrentValue(PairState* state) {
 	KeyValuePair* current = state->pairs + state->index;
-	state->current = current->value;
-	state->end = current->value + current->valueLength - 1;
+	state->current = (char*)current->value;
+	state->end = (char*)current->value + current->valueLength - 1;
 }
 
 // Switches from writing to the current key to the current value. Ensures that
@@ -185,8 +185,8 @@ StatusCode fiftyoneDegreesYamlFileIterateWithLimit(
 		keyValuePairs,
 		collectionSize,
 		0,
-		keyValuePairs[0].key,
-		keyValuePairs[0].key + keyValuePairs[0].keyLength - 1 };
+		(char*)keyValuePairs[0].key,
+		(char*)(keyValuePairs[0].key + keyValuePairs[0].keyLength - 1) };
 
 	// If there is no limit then set the limit to the largest value to 
 	// avoid checking for negative values in the loop.
@@ -301,6 +301,5 @@ StatusCode fiftyoneDegreesYamlFileIterate(
 		collectionSize,
 		-1,
 		state,
-		callback
-	);
+		callback);
 }
\ No newline at end of file