C ELM31A              POINTER INDICES FOR MARKER ELEMENT
C
C NMARK      POSITION OF MARKER FOR CURRENT LOCATION
C NMARKS     MARKER NUMBER OF PRESENT MARKER
C NMARKB     POSITION OF FIRST ELEMENT REFERRED TO BY MARKERS
C NMARKE     POSITION OF LAST ELEMENT REFERRED TO BY MARKERS
C MKG        INDICATES WHETHER MARKER IS BEING PROCESSED
C DRC        TRUE IF ALGEBRAIC EXPRESSION IS FOR PRESENT MARKER
C MKDO       TRUE IF OPERATION IS FOR PRESENT MARKER
C
      INTEGER         NMARK, NMARKS, NMARKB, NMARKE
      LOGICAL         MKG, DRC, MKDO
C
      COMMON /ELM31A/ NMARK, NMARKS, NMARKB, NMARKE, MKG, DRC, MKDO