The title says it all: the spec for the glDrawRangeElementsBaseVertex function is rubbish.
glDrawRangeElementsBaseVertex is a restricted form of glDrawElementsBaseVertex.
mode, start, end, count and basevertex match the corresponding arguments to glDrawElementsBaseVertex, with the additional constraint that all values in the array indices must lie between start and end, inclusive, prior to adding basevertex.
glDrawElementsBaseVertex doesn’t have a start or end argument. Perhaps the above should say “mode, count, type, indices and basevertex”, since type and indices seem to have the same meaning for both functions?
Index values lying outside the range [start, end] are treated in the same way as glDrawElementsBaseVertex
But… you just said that all the index values must be inside that range. Perhaps substitute “outside” with “inside” to make this sentence make sense?
Does no-one proof-read this stuff? bug submitted.
Update: so it turns out that ‘in the same way as glDrawElementsBaseVertex’ is supposed to mean ‘in an implementation-defined manner consistent with how similarly out-of-range indices are treated by glDrawElementsBaseVertex’. I feel like the wording could be much clearer but I’m not going to argue this one. The parameter specifications are clearly incorrect and this should be fixed in a revision.