Works - thank you

Upon change:

set %out="" for { ##continue
         set key=$order(%array("")) quit:key="" ##continue
        set %out=%out_%del_key}

Call is: $$$ArrayToString(pQArray,tQStr,"##")

Just for 3 rows array, it creates infinitive string ending in MAXSTRING error

Upon change:

set %out="" for { ##continue
         set key=$order(%array(key)) quit:key="" ##continue
        set %out=%out_%del_key}

Call is: $$$ArrayToString(pQArray,tQStr,"##")

ERROR #5002: ObjectScript error: <UNDEFINED>zTrans+22^HS.Local.VA.Util.SQLHub.1 *key