What is the meaning of a colon in the field name in the OnyxOs Data Guide

Q: In the OnyxOS Data Guides some fields use a colon (:) to concatenate a field name. Does this have a special meaning?

The FHIR Specification has the capability to specify multiple meanings for fields that may have multiple entries. An example of this would be a business identifier. The colon (:) in this situation indicates a “Slice”. That is an element can have a specific definition. For example, the first business identifier may be a National Identifier, such as a National Provider Identifier (NPI). Therefore, each slice defines the data that should be provided when providing the particular type of identifier. This can be considered an advanced topic in the FHIR Specification. More information can be found here: Slicing in Profiles