China Odd & Unusual Perforations thru stamp - Need ID

[Pocket Change]

This is one that I had in about 25 China stamps I had several years ago. Appreciate any help.

 

[Mackaydon]

PC: As you noted, the perfs are odd--and there is no denomination marked on the stamp.
All of which suggests to me the stamp is a not a POSTAGE stamp but one used for another (unknown) purpose.
Don......