lua_getglobal function argument

[saito yutaka <melody.pea@...>]

Hello .
I am trying to read lua.c to want know how lua works.
And I want to ask about lua_getglobal function.

I find a this code .
  lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");

I know that this code means get a value PROMPT("> ") or PROMPT2(">> ") .
But why does it use underscore [ _ ] front of global names ?

Thanks.
Yutaka

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