Index of types

`BaseDef refers to META definitions using the "=" operator, and `Appendix refers to definitions using the "+=" operator.

A formal predicate as it occurs in a package definition

The definition of a package

A pkg_definition is expressed by the syntax

 var(p1,p2,...) = "value" 

(flavour `BaseDef), or the syntax

 var(p1,p2,...) += "value" 

(flavour `Appendix) in the META file.

A value of type pkg_expr denotes the contents of a META file.