Arguments
DEG:  CHARACTER*3 array of length 3 containing maybe formatted
number.  The minus sign (if any) is placed in the 1st col.
IMIN: INTEGER*4 minutes output
SEC:  REAL*8 seconds output
DDEG: REAL*8 degrees, to be converted to dms format as used
in DMS2D
IDIGIT: number of significant digits to the right of the decimal
point in seconds.  D2DMS will adjust the output so that
the 'seconds' are always less than 59.0 - 0.5*10**-IDIGIT.
Must be restricted to (-2 to +4).  Thus, if the seconds are
printed using format Fm.IDIGIT, they will come out strictly
less than 60.