P-Lingua format

From The P-Lingua Website

Valid identifiers

We say that a sequence of characters forms a valid identifier if it does not begin with a numeric character and it is composed by characters from the following:

a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
0 1 2 3 4 5 6 7 8 9 \_

Valid identifiers are widely used in the language: to define module names, parameters, indexes, membrane labels, alphabet objects and strings.