diff --git a/Documentation/ImplementersDocumentation/DataTypes.md b/Documentation/ImplementersDocumentation/DataTypes.md
index 25c7cea..215cdd9 100644
--- a/Documentation/ImplementersDocumentation/DataTypes.md
+++ b/Documentation/ImplementersDocumentation/DataTypes.md
@@ -279,7 +279,7 @@ Columns of the table determine the validity of the type depending on the schema
| IFCRATIOMEASURE | ✓ | ✓ | ✓ | xs:double |
| IFCREAL | ✓ | ✓ | ✓ | xs:double |
| IFCRECURRENCETYPEENUM | | ✓ | ✓ | xs:string |
-| IFCREFERENTTYPEENUM | | ✓ | ✓ | xs:string |
+| IFCREFERENTTYPEENUM | | | ✓ | xs:string |
| IFCREFLECTANCEMETHODENUM | ✓ | ✓ | ✓ | xs:string |
| IFCREINFORCEDSOILTYPEENUM | | | ✓ | xs:string |
| IFCREINFORCINGBARROLEENUM | ✓ | ✓ | ✓ | xs:string |
@@ -373,7 +373,7 @@ Columns of the table determine the validity of the type depending on the schema
| IFCUNITARYCONTROLELEMENTTYPEENUM | | ✓ | ✓ | xs:string |
| IFCUNITARYEQUIPMENTTYPEENUM | ✓ | ✓ | ✓ | xs:string |
| IFCUNITENUM | ✓ | ✓ | ✓ | xs:string |
-| IFCURIREFERENCE | | ✓ | ✓ | xs:string |
+| IFCURIREFERENCE | | ✓ | ✓ | xs:anyURI |
| IFCVALVETYPEENUM | ✓ | ✓ | ✓ | xs:string |
| IFCVAPORPERMEABILITYMEASURE | ✓ | ✓ | ✓ | xs:double |
| IFCVEHICLETYPEENUM | | | ✓ | xs:string |
@@ -408,6 +408,7 @@ The list of valid XML base types for the `base` attribute of `xs:restriction`, t
| Base type | Value string regex constraint | annotation | pattern | enumeration | minLength | maxLength | length | minExclusive | maxExclusive | minInclusive | maxInclusive |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------- | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: | :-----------: |
+| xs:anyURI | ^\S+$ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | | | | |
| xs:boolean | ^(true|false|0|1)$ | ✓ | ✓ | | | | | | | | |
| xs:date | ^\d{4}-\d{2}-\d{2}(Z|([+-]\d{2}:\d{2}))?$ | ✓ | ✓ | ✓ | | | | ✓ | ✓ | ✓ | ✓ |
| xs:dateTime | ^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|([+-]\d{2}:\d{2}))?$ | ✓ | ✓ | ✓ | | | | ✓ | ✓ | ✓ | ✓ |
diff --git a/Documentation/UserManual/specifications.md b/Documentation/UserManual/specifications.md
index 59a5f50..1763976 100644
--- a/Documentation/UserManual/specifications.md
+++ b/Documentation/UserManual/specifications.md
@@ -28,6 +28,7 @@ A **Facet** describes its information precisely using fixed **Facet Parameters**
When a **Facet** is used in the **Applicability** section, it describes the information that we use to identify the relevant parts of the model.
When a **Facet** is used in the **Requirements** section, it describes the information constraints that the model parts must fulfill to comply with the **Specification**.
+Each facet in the requirements can be enriched with an optional `instructions` text to help end-users complete the model.
