So my first step was to get rid of the line continuations and break it into the SELECT, FROM, & WHERE statements.
SELECT AL1.PRP_BEZ, AL1.PRP_VAR, AL1.PRP_VER, AL1.RUN_DATE, AL1.RUNID, AL3.MRK_NUM_EXT, AL3.MRK_BEZ, AL3.MRK_WERT, "AL3.MRK_EINHEIT, AL3.MRK_EIN_GUT, AL2.MRK_TXT...