man mplist_add () - Add a property at the end of a property list.
NAME
mplist_add - Add a property at the end of a property list.
SYNOPSIS
MPlist* mplist_add (MPlist * plist, MSymbol key, void * val)
DESCRIPTION
The mplist_add() function appends at the end of property list plist a property whose key is key and value is val. key can be any symbol other than Mnil.
If key is a managing key, val must be a managed object. In this case, the reference count of val is incremented by one.
RETURN VALUE
If the operation was successful, mplist_add() returns a sublist of plist whose first element is the just added one. Otherwise, it returns NULL.