This is a library of similar procedures to filter data input in normal edit controls.
There are seven modules in the library that handle some of the more common cases of filtered input.
lower case only
upper case only
alphabetical only
alphanumeric only
no numbers
numbers only
text only
There are many other ranges of filtering that can be done which is application specific but the same mechanism can basically be used, subclass the edit control and process the WM_CHAR message.