Key words: mapu & mapt

Dear FreeFEM user,

Can someone tell me the meaning of mapu=[ ] in the following expressoin, unfortunately I cannot find these key words from FreeFEM++ manual.

varf ab( [u,v,p], [lamxh,lamyh,Xh,Yh] ) =
int2d(Ths, qft=qf9pT, mapu= [Xo,Yo])(
+ c2

Best wishes,

I add this fo special scheme, for this article:
Distributed Lagrange Multiplier for Fluid-Structure Interactions
with O. Pironneau a A. Boffi

Thank you very much Hecht!
That’s it. Olivier sent me this code.
I am trying to use interpolation rather than Boffi’s Lagrange Multiplier.