Identifiers are simply names assigned to variables and functions. An identifier must start with a letter or an underscore (_) eventually followed by one or more letters, numbers, underscores and dots.
Valid identifiers are:
foo
Bar
foo.bar
my_var
_my_var
Important: Cows defines some internal variables beginning with the underscore character. In order to avoid clashes with future versions you'd better avoid using the underscore character at the beginning of a variable name. Current version of Cows defines the following variables:
An array storing months' names
An array storing week days' names
The number of arguments passed to an included file
Arguments passed to an included file
This manual can be downloaded from http://www.g-cows.org/.