Vincent,
I will tell you the situation.I have one character field.This field should contain 'characters and then followed by numbers'.For example the field should contain the value of 'PRQ1234'.I am extracting the string after PRQ in a temporary field.So,the temporary field will have value if 1234 in this case.But, if this temporary field contains a value other than numbers,then the user should get a error message.
Regards,