This format is related to the TrueType format
The nature, manipulation, and use of these TFMs is thoroughly described in the Hewlett Packard PCL 5 Developer’s Guide (part number 5967- 0546) which is available by calling HP Parts Direct at 1-800-227-8164. The current cost for the manual is listed at $60.00 U.S. currency.
Please note that on page 8-11 of the Hewlett-Packard PCL5 Developer’s Guide, the formula listed for calculating TFM data has an error. The parenthesis in the second equation should read:
x = round(d/e * EMsize) * uom/dpi
While using the internal scalable fonts, be careful to note which of the fonts use True Type units of measure (1 point = 1/72 inch) and which use the Intellifont units of measure (1 point = 1/72.307). The Areal, Times New Roman, Symbol, and WingDings typefaces use the True Type point measurement. All others use the intellifont measure.