Acceptable indicies

[liam mail <liam.list@...>]

"Most query functions accept as indices any value inside the available
stack space ..." [1]
Would it be correct to say, "all functions which take a stack index
require that it is inside the available stack space", or are there
exceptions to this? I ask because functions such luaL_opt*[2] and
luaL_check* [3] do not mention they require acceptable indicies and
ones which are not acceptable result in undefined behaviour, whilst
nearly all other functions that take indicies are noted they have a
precondition of an acceptable index.

For example
if lua_gettop equals 0
    luaL_checkany(L,-1) is undefined.
or when stackspace equals X
    luaL_checkany(L,X+1) is undefined.

[1] http://www.lua.org/manual/5.1/manual.html#3.2
[2] http://www.lua.org/manual/5.1/manual.html#luaL_optint
[3] http://www.lua.org/manual/5.1/manual.html#luaL_checkany

Liam