Definition of Programmatically Determinable (#1315)

* Include SC 1.3.5 in criteria applicable to "programmatically determinable"

pages/structure/accessibility-support.md

@@ -44,10 +44,11 @@ There are two concepts that must work together to ensure that information can be
 
 Content: MUST Work with AT:
 
-Five SC require that content must be "programmatically determinable." This means that the content is authored in such a way that user agents, including assistive technologies, can access the information.
+Six SC require that content must be "programmatically determinable." This means that the content is authored in such a way that user agents, including assistive technologies, can access the information.
 
 - 1.3.1: Info and Relationships
 - 1.3.2: Meaningful Sequence
+- 1.3.5: Identify Input Purpose (AA)
 - 3.1.1: Language of Page
 - 3.1.2: Language of Parts (AA)
 - 4.1.2: Name, Role, Value