char-property-alias-alist

char-property-alias-alist is a variable defined in `C source code'.
Its value is

nil

Documentation:
Alist of alternative properties for properties without a value.
Each element should look like (PROPERTY ALTERNATIVE1 ALTERNATIVE2...).
If a piece of text has no direct value for a particular property, then
this alist is consulted. If that property appears in the alist, then
the first non-nil value from the associated alternative properties is
returned.