You can find it in the File Layouts guide in Sage 100.

do i need to have a sage100 system to get the api documentation?

The files referenced by Sage100user are version specific, so you should really be looking at version specific information... but here is a link for v2018.

http://help-sage100.na.sage.com/2018/FLOR/Content/HomePage/Welcome.htm

I have checked the link given and it is a parameter and I think that is not a api documentation.

Is  there a more specific api documentation for sage 100 like sage intacct developer.intacct.com/.../

Can you describe what your purpose is?

This is for research on the API documentation of different accounting systems.

Try this link.

http://help-sage100.na.sage.com/2018/FLOR/index.htm#Object_Reference/HomePage/Welcome.htm%3FTocPath%3DObject%2520Reference%7C_____0

On the left side, it will list each module and under the module it will list the objects.