A regular expression (regex for short) is a special text string for describing a search pattern, it is standardized and can be use in any device that supports regex.
SGOS uses a standard regex syntax, however, some symbols in regex syntax (e.g. [, ], * and etc.) have purpose and meaning in standard CPL policy expressions.
So if your regex requires to use some of this characters or symbols, a double-quotation (") mark at the start and the end of your regex is required.
If your regex does not contains these special characters or symbols, you can use it without the double-quotation (") mark.
This is by design, and usual practice is to include the double-quotation (") mark for regex search pattern.
For more information on Regular Expressions, see Appendix E: Regular Expressions in the CPL reference guide for your version of SGOS.