What is a long section (fragment)? #pragma section (".rdata$T", long, read)

What does long and short mean in the context of sections in the object file? It seems to refer to its size, but there is no documentation on it. Here we see the section name .rdata$T is long, but I don't know what that means, and whether it applies to .rdata as a whole or just the fragment .rdata$T.