This macro creates a datum symbol of the type needed for the ASME-Y14.5 1994 standard or the ISO-1101 standard. In addition to creating the datum, the macro also automatically creates a leader line to the reference element. The leader line can be drawn horizontally from the datum to the reference element, vertically from the datum to the reference element, or it can come out from the datum a short distance either horizontally or vertically and then be perpendicular to the reference element. Limitations: *The size of the datum, its color, linespace and ratio are *Th: dependent on whether ARROW_FILL is ON or OFF.