Schedule 4 forms part of the definition of the legislative competence of the Scottish Parliament.  Section 29(2)(c) provides that a provision of an Act of the Scottish Parliament is outside the legislative competence of the Parliament if it is in breach of the restrictions in Schedule 4.  The restrictions are upon the extent to which certain enactments - including provisions of the Scotland Act 1998 itself - and other aspects of the law may be modified by an Act of the Scottish Parliament.  The schedule also sets out some modifications of sections 53 and 54 (which provide for the general transfer of functions exercisable within devolved competence to the Scottish Ministers).
Purpose and Effect