Update gene-product-information-gpi-format-20.md

fixing col 1 description

_docs/gene-product-information-gpi-format-20.md

@@ -75,14 +75,15 @@ ncRNA:
 ### Definitions and requirements for field contents
 
 #### 1. DB:DB Object ID
-The **DB** prefix is the database abbreviation (namespace) from which the unique identifier **DB Object ID** is drawn and must be one of the values from the set of GO database cross-references. The **DB:DB Object ID** is the combined identifier for the database object.
+A unique identifier for the item being annotated. The **DB** prefix is the database from which the **DB Object ID** is drawn and must be one of the values from the set of GO database cross-references. The **DB:DB Object ID** is the combined identifier for the database object. Examples:
 
-This field is mandatory, cardinality 1.
+* `UniProtKB:P99999`
+* `SGD:S000002164`
+* `MGI:MGI:1919306`
+
+The identifier usually references the canonical form of a gene or gene product including functional RNAs.  Identifiers may also describe gene variants, distinct proteins produced by to differential splicing, alternative translational starts, post-translational cleavage or post-translational modification. If the gene product is not a canonical gene or gene product identifier, the Gene Product Information (GPI) file should contain information about the canonical form of the gene or gene product.
 
-<!--In GPI 1.0 format, the identifier may reference a top-level primary gene or gene product identifier, or an identified variant of a gene or gene product, for example identifiers that specify distinct proteins produced by differential splicing, alternative translational starts, post-translational cleavage, or post-translational modification. Identifiers for functional RNAs and protein complexes can also be included in this column. 
-    If the gene product is not a top-level gene or gene product identifier, the **Parent_Object_ID** field should contain the canonical form of the gene or gene product. 
-    Note that while the **DB_Object_ID** is the identifier for a database object that may be used for annotation, it may or may not correspond exactly to what is described in a paper. For example, a paper describing functional characterization of a protein may result in annotations to the gene encoding the protein (gene ID in **DB_Object_ID**) or annotations to the protein (protein ID in **DB_Object_ID**), depending on annotation practice of the contributing group. 
--->
+This field is mandatory, cardinality 1.
 #### 2. DB Object Symbol
 A (unique and valid) symbol to which the **DB:DB_Object_ID** is matched. No white spaces allowed.