The Magic Prefix
The prefix is quite a character. It is always at the front of the line, and does not suffer from low self-esteem like the suffix.
It is indispensable in identifying information. If you use a prefix for your data, you will never put part number data into the quantity column. It is elegant in its simplicity. If you want to identify a part number, then a 'P' should be the prefix. You can use 'Q' for quantity, 'S' for serial and 'L' for location.
The prefix is not actually data, but is a really neat trick for identifying data when you are using bar codes. This bar code will read 'Q20' when scanned by a bar code reader but the actual quantity is '20'. When the bar code is scanned the software will be looking for the prefix 'Q' and then know that the quantity is '20' and will then store '20' into the database.
If the software is asking the user for quantity and the user accidently scans a bar code with the part number, then the software will ignore that can and politely ask the user to scan the correct bar code.
So the magic prefix does its job quite admirably and ensures that the database remains as pure as humanly possible.