Enum om\RRule\Skip

`implements`	`BackedEnum`

SKIP rule part (RFC 7529, section 4.1): handling of instances on an invalid date, e.g. February 30 or February 29 in a common year.

Located at RRule/Skip.php

Cases
`Omit = 'OMIT'` The instance is dropped (the RFC 5545 behaviour). The instance is dropped (the RFC 5545 behaviour).	#
`Backward = 'BACKWARD'` The instance moves to the previous valid day, the last day of the month. The instance moves to the previous valid day, the last day of the month.	#
`Forward = 'FORWARD'` The instance moves to the next valid day, the first day of the next month. The instance moves to the next valid day, the first day of the next month.	#