Regular expression syntax
Regular expression  Description 

a  a where a is any symbol excluding symbols ()[].*+^$\? 
\a  a where a is any symbol including ()[].*+^$\?
To represent any symbol "as is", prefix it with a backslash symbol. You can use it to represent special characters, including characters inside of CharSet. To represent a single backslash character ( \ ), prefix it with itself ( \\ ). For example: \* means character "*" and \a means character "a". 
.  Any single symbol.
For example: expression 11.5 corresponds to such combinations of characters as "1135", "11f5", "11_5" and so on. 
RegExp  Any regular expression RegExp.
For instance, 112 represents sequence "112", which can be found inside a string (not the whole string!). 
RegExp1RegExp2  Any one of expressions RegExp1 or RegExp2
For example, expression 13 validates any of symbols "1" or "3". Note: Concatenation has priority over alternation. This means that combination 12.578 corresponds
"(12(any number)5)
or (78)". So, the representations of this example can be: "1235", "12f5", "78".

RegExp+  Regular expression RegExp repeated one or more times.
Use this expression to find sequences of desired characters. For example, (13)+ will find expressions (13), (13)(13) and so on. 
RegExp*  Regular expression RegExp repeated zero or more times. 
RegExp?  Regular expression RegExp repeated zero or one time. 
RegExp1RegExp2  Sequence of two expressions: RegExp1 then RegExp2.
For example, (13)(11.5) corresponds to such combinations as "11175", "311t5" and so on. 
^  Beginning of string.
Use this symbol to find strings which begin with predefined regular expression. The desired expression must follow ^ sign. For example:

$  End of string.
Use this symbol to find strings which end with predefined regular expression. The desired expression must precede $ sign. Expression ^RegExp$ corresponds to the whole string only. For example:

[CharSet]  Any single symbol belonging to a character set CharSet.
The CharSet is specified as a character string and includes all symbols of the string. The order of characters doesn't matter. A "" sign inside of the CharSet has a special meaning and is used to represent a characters interval. For example, expression [12ae34] means the same as [12abcde34], it stands for any character "1", "2", "3", "4", "a", "b", "c", "d" or "e". 
[^CharSet]  Any symbol not belonging to manifold CharSet.
For example, [^12ae34] means any character excluding "1", "2", "3", "4", "a", "b", "c", "d" and "e". Note: Other symbols inside brackets are considered as characters but not special symbols.
For instance, [$] is not a
symbol of end of string but it is a character "$”.
Symbol ^ must stand right after "[", otherwise it means just a character "^”. 