Field Validation on Product Manager

[rhysdavies]

I am using Product Manager 2.2 on CMSMS 1.5.2 and I want to be able to write in alphanumeric (text/numbers) in the 'weight' field.  At present, the scripts default this field to numeric only.  I have changed the field type from 'DOUBLE' to 'VARCHAR' on the MySQL database, and I can write this field alphanumerically in the database, but it still doesn't want to know when using the admin panel.  I suspect it's something in the php scripts, but I'm damned if I can find where it is.

TIA