$helptxt['custom_mask'] = 'The input mask is important for your forums security. Validating the input from a user can help ensure that data is not used in a way in which you do not expect it. We have provided some simple regular expressions as hints.
<span class="smalltext">
"[A-Za-z]+" - Match all upper and lower case alphabet characters.
"[0-9]+" - Match all numeric characters.
"[A-Za-z0-9]{7}" - Match all upper and loser case alphabet and numeric characters seven times.
</span>
Additionally, ?+* and {xx} mean how much to match of the expression.
<span class="smalltext">
? - None or one match of previous expression.
+ - One or more of previous expression.
* - None or more of previous expression.e
{xx} - An exact number from previous expression.
{xx,} - An exact number or more from previous expression.
{,xx} - An exact number or less from previous expression.
{xx,yy} - An exact match between the two numbers from previous expression.
</span>
';