== rca space == 

 I followed a wikilink to "rca space", which redirected me to "ba space". But the ba space article makes no mention of any rca space. So what's rca space? Is it the same thing, or an older term for the same thing, or something slightly different? Could somebody (perhaps whoever ordered or okayed the redirection, for example) PLEASE define "rca space" within the "ba space" article ! Or recreate the alternative page. Either/or, for clarity, so that the term makes sense rather than just leaving a mystery.