+deltaPlusMinusTimeExpr
+ : countUnitsBeforeAfterTimeExpr
+ | fractionBeforeAfterTimeExpr
+ ;
+
+countUnitsBeforeAfterTimeExpr
+ : nth (SPACE+ deltaTimeUnit)? SPACE+ deltaTimeBeforeAfter
+ ;
+
+fractionBeforeAfterTimeExpr
+ : deltaTimeFraction SPACE+ deltaTimeBeforeAfter
+ ;
+
+deltaUnit: (YEAR|MONTH|WEEK|DAY|WEEKDAY|WORKDAY) ;
+
+deltaTimeUnit: (SECOND|MINUTE|HOUR|WORKDAY) ;