HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part II

EN LO, Label Origin 23-65
The pen position at the end of the label string depends on whether
two successive LB commands concatenate together as though only
one label was given. The DV/LO combinations which permit
concatenation are:
The following two rules determine where the pen is positioned after a
label string is drawn. Rule 1 is for DV/LO combinations which permit
concatenation; rule 2 clarifies other DV/LO combinations:
1 If a concatenation combination is specified, the pen position is
updated to give the normal delta X space between the last
character of the first label, and the first character of the second
label.
Note For proportional fonts that use a pair-wise spacing table, the pen
position is updated using an average delta X space.
2 If a non-concatenation combination is specified, the pen position
that existed immediately prior to the LB command is restored.
Table 23-35
Text Path Label Origin
DV0 (right) LO’s 1,2,3, and 11,12,13,21
DV1 (down) LO’s 3,6,9, and 13,16,19
DV2 (left) LO’s 7,8,9, and 17,18,19
DV3 (up) LO’s 1,4,7, and 11,14,17,21