Role played by another role

[BFergerson]

Thinks role (has_defines/is_defines) isn't played but it's played by another role extending it:

defines is-abstract sub relationship
    relates has_defines, relates is_defines
    has create_date
    has start_offset
    has end_offset;
has_defines sub role;
is_defines sub role;

defines_file sub defines
    relates has_defines_file, relates is_defines_file;
has_defines_file sub has_defines;
is_defines_file sub is_defines;

defines_function sub defines
    relates has_defines_function, relates is_defines_function;
has_defines_function sub has_defines;
is_defines_function sub is_defines;