How to bulid a new style region?

Dear Pim:
Would you like to help me build a new style region?
I want to build up a Elliptic shape region.I can use C language to write a Elliptic.However , what i can print out is the coordinate of the point of the Elliptic.I do not know how to put these datas in lammps.
I find that the format of the read_data is not the one i need, i only want to build a new region without atoms.
Can you sent the source code of the region command to me or just tell me how to do ?

many thanks!

If you have downloaded LAMMPS, you have
the source code for the region command. See


You can add a region ellipssoid, by starting
with a file like region_sphere.cpp and making