URL Mapping reference: Valid URL characters

Context names and identifiers must only consist of characters that are contained in the set of unreserved URL characters.

The set of unreserved URL characters that you can use for context names and identifiers are listed in the following:

Alphanumeric characters:
  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
Special characters:
Description Character
Hyphen -
Underscore _
Period .
Exclamation mark !
Tilde ~
Asterisk *
Single quote '
Parentheses open and closed ( )