Local and Global Variable Names

PML variables are of two kinds: global and local.

Global variables last for a whole session (or until you delete them). A local variable can be used only from within one PML Function or macro.

These two kinds of variable are distinguished by their names. Names beginning ‘!!’ are global; names beginning ‘!’ are local:

!SurfaceArea

!!Area

PML Variable names may be any combination of letters and digits, starting with a letter, up to a maximum of 64 Unicode characters (plus the ‘!!’ or ‘!’). Names are allowed to contain a dot (.) but this is now strongly discouraged as a dot has a special meaning in PML2 as a separator between an object and its methods (see Using the Methods of an Object), and between the components of form and gadget names.

Rather than using a dot as part of a name we recommend that you use a mixture of upper and lower case to make variable names more meaningful, for example:

!!StartInUpperCase