What is Validation Expression?

[lmureca]

Hey there,
   I was wondering if anyone could shed some insight on the purpose of the "Validation Expression" field.  When one goes to add a new attribute "validation Expression" comes up as one of the configurable parameters along with things such as "type", "display label", and "sort order".  Does anyone know what The validation expression does ?  Thanks for any help or comments.
-Best

[Nick]

Sorry, that's poorly documented. This is a regular expression that can be used to enforce rules on the data being entered for that attribute. You can use this to limit the length of the input, restrict to numbers only, specific formats, etc.