As only the Locator and Stroke logical devices return coordinate values, only these two have 3D versions of the routines used for the three input modes. Thus, for request mode, the calls are:
CALL GRQLC3(WKID, LCDNR, STAT, TNR, VWI, PX, PY, PZ)
and
CALL GRQSK3(WKID, SKDNR, STAT, N, TNR, VWI, NP, PX, PY, PZ)
Where, apart from the extra dimension, PZ, the only difference to the
2D calls is the addition of the View Index, VWI.
(Note that as for TNR, VWI is an output parameter.)
This corresponds to the index of the viewing attribute bundle used to
convert the position(s) back from NPC3 coordinates to NDC3 coordinates.
Of course, when using a physical 2D device, it is awkward for the user
to provide the third coordinate for 3D input.
Although only Locator and Stroke have 3D functions to obtain input, all six logical devices have 3D versions of the initialization functions. For example, these allow the echo areas to be positioned in space, rather than in a plane. They will not be discussed further in this Primer.