Is a girl

is_a_girl is an variable used in character assignment files, first introduced in Lego Star Wars II: The Original Trilogy. As the name implies, it generally indicates that the character is female.

Lego Star Wars: The Complete Saga
is_a_girl changes the default personal sound effects to female (Leia's in vanilla), which will be used unless other sounds are specified in the character's TXT file.

Lego Indiana Jones:The Original Adventures
In addition to changes the default personal sound effects to female, a character who is_a_girl will be unable to be targeted by friendly males. While only females are able to jump high in vanilla LIJ1, this is controlled by their jump height property, rather than is_a_girl.