is an option for functions which use level specifications that specifies whether heads of expressions should be included.
- Heads->True treats heads just like other elements of expressions for the purpose of levels.
- Heads->False never includes heads as part of any level of an expression.
- Most functions which use level specifications have the default setting Heads->False. One exception is Position, for which the default is Heads->True.
Examplesopen allclose all
Introduced in 1991