Catalog number
Marked on devices as "Model Number".
Every officially released TI product for the TI99/4a carried a catalog or model number in the form PHXNNNN, as follows:
PHA was used for Accessories
PHC was used for Consoles.
PHD was used for programs supplied on disks.
PHL was used for "software albums"
PHM was used for command modules.
PHP was used for Peripherals.
PHT was used for software supplied on cassette tapes.
See also Serial number