2.1.7.12 Custom Property
The Custom Property part is specified in [ISO/IEC29500-1:2016], section 12.3.5.
In addition to the explicit relationships specified in [ISO/IEC29500-1:2016], section 12.3.5, a Custom Property part is permitted to be the target of an explicit relationship from the following parts specified by this document:
Macro Sheet (section 2.1.7.32)