SAP delivers standard implementations of change documents for Personnel
Planning infotypes:

Standard Implementation CL_HRBAS_CDOCEXT_HANDLER

Standard Implementation CL_HRBAS_CDOC_IT1001_HANDLER
If you use one of the standard implementations, an infotype is fully connected
to the change document solution. You do not need to write an additional
infotype-specific code. The standard implementations are made available in
the form of ABAP classes (document object classes). In the case of other
solutions, you can pass the properties of the ABAP classes onto the solution
and enhance or redefine existing methods or implement entirely new ones.
Each infotype for which change documents are created is assigned one
document object class in table T77CDOC. You can also assign a document
object class to customer infotypes. For more information, see Creation of
Change Documents for Customer-Specific Infotypes.
In Customizing table T77CDOC_CUST (Activate Creation of Change
Documents) you can activate the creation of change documents for specific
infotypes, plan versions, object types, and subtypes. For more information,
see Customizing Settings for Creation of Change Documents.
In the standard system, the creation of change documents is deactivated for
all infotypes. You can only activate infotypes that have been prepared for the
creation of change documents, that is those infotypes for which a valid entry
exists in table T77CDOC.