Strange plane

[blackhat]

At least to me.  Sorry I can't do pics until I get home but.....I picked up a rather crudely made wooden jointer except, it has a groove, not quite centered, 3/4" wide and 1/4" deep running the length of the sole.  Probably the cleanest bit of work on the plane, everything else is crude, functional but crude.  Any ideas on what the maker was trying to achieve?

[bandit571]

Tongue & groove planes used to be a hair off-set.  That way, the thicker part was above the tongue your plane would make.  Comes in handy  when doing wood floors.