My "guess" is that it is "center off". From bottom view:
When to the left, those two left most contacts are connected. That defines the spacing of the sliding contacts. In the middle, the contacts on the left side are in "empty space" between the other two wide spaced ones. When the switch is to the right, the pins to the far right are connected to the second from the left (same spacing).
Most sliding switches have fixed wipers, fixed distances. Some have multiple contacts, like shorting contacts, so other possibility is left, connect left two sets, middle, short out middle two sets, far right, shorts out 3 rightmost sets.
Only with an ohm meter can you really test and determine how the switch is configured.