Sliding door security and child safety latch

A latch for maintaining a sliding door in one of several modes such as a child-safety mode. When in the child-safety mode, the range of motion of the sliding door is restricted, however, the latch may be disengaged by an adult from either side of the sliding door. The latch may also be employed in a security mode to prevent any opening of the sliding door from the exterior side. The latch may additionally be employed in a ventilation mode wherein the sliding door is slightly opened with overriding of the latch available only from the interior of the sliding door.