# Technical Notes

READ-ONLY FIELDS & ODBC (not included in filePro Lite)

filePro recognizes fields marked as "read-only" from the ODBC data source, and will not allow you to modify them. If placed on the screen, filePro will automatically treat it as protected. You cannot assign to such fields in processing.

Microsoft SQL Server does not return a read-only status on read-only fields. Rather, every field is listed as "writable_unknown", meaning it is not known whether the field is writable or not. Unfortunately, since every field is listed this way, filePro must treat "writable_unknown" as "writable". Modifying read-only fields marked this was is not stopped by filePro, and will lead to SQL errors.

NULL SQL Values

ODBC returns NULL SQL values by using specific "pseudo-NULL" C values. Unfortunately, there is no way we currently know of to distinguish between a pseudo-NULL value and a field containing that same non-NULL value. For example, long-integer NULL values are returned as 1,246,576,928. If a long-integer field happens to contain 1,246,576,928, there is no way to distinguish that from the pseudo-NULL value. For now, filePro will not do anything special with such values, and NULL values will appear with their pseudo-NULL values.

PFLONGVARDOT=OLD

filePro used to accept a period in variable names. This is now not allowed (it never should have been allowed in the first place), in order to permit enhanced functionalities. To revert to the old behavior and allow periods in variable names, you can set PFLONGVARDOT=OLD. Note, however, that this will disable certain features, such as access to ODBC and biometrics, which require that periods not be allowed here.