HP PCL 5 Reference Manual page 239

Character Width (UI)
The Character Width, used for bitmap fonts only, identifies the width
of the character in dots on the physical coordinate system. Generally,
this width is from the farthest left black dot to the farthest right black
dot. Character width is orientation dependent.
The legal range for character width is 1 to 16384 dots.
Character Height (UI)
Character Height specifies the height of the character in dots on
the physical coordinate system. Character height is orientation
dependent.
The legal range for character height is 1 to 16384 dots.
Delta X (SI)
Delta X specifies the number of quarter dots (radix dots) by which
the horizontal position within the logical page coordinate system is
incremented after printing the character. This value is only used by
the printer when the font is proportionally spaced.
The legal range for delta X is –32768 to 32767 quarter units.
Character Data
Character data is a string of bytes containing the dot-per-bit image of
the character or a run-length encoding with line repetition
compressed format.
Character Descriptor Formats 11-57
EN