MACSYM and MONSYM are needed to assemble KLDDT.
Use RQDATE instead of .RDATE to get the full year. The previous version was presumably written in 1972, breaking 28 years later in 2000. The updated version will stop working in 2052 due to TOPS-10 limiting the returned value to 15 bits.
MACRO-10 53A(1152) from 19-JUL-1979.