4.1.4 Variables

Variables may be written as any sequence of alphanumeric characters (including '_') beginning with either a capital letter or '_'. For example:

                      X   HiLog   Var1   _3   _List

If a variable is referred to only once in a clause, it does not need to be named and may be written as an anonymous variable, represented by a single underscore character '_'. Any number of anonymous variables may appear in a HiLog clause; all of these variables are read as distinct variables. Anonymous variables are not special at runtime.