Does anyone know what a 'reversion' is?

[Jeremy Nicoll - ml get_iplayer]

I've noticed that a few BBC programmes are described as 'reversions'.  For
example there's a repeat (or maybe it's more than that?) of Series 5 of "Rip
Off Britain" on at the moment.  In the tv.cache file (& on the BBC website)
the episodes are titled:

  Rip Off Britain: Series 5 (Daytime Reversions)

The tv.cache file currently lists some other 'reversions':

  Coast: Series 5 Reversions

  Flog It!: Series 7 Reversions

  Flog It!: Series 9 Reversions

  Flog It: Trade Secrets: Series 2 - Reversions

Presumably there's more to these than just repeats... but what?  I watched a
couple of the Rip Off Britain ones and had the impression that I'd seen the
whole of the programmes before a few months ago, though that doesn't
preclude subtle editorial changes or omission of previous material.  

I did email the BBC to ask (without mentioning get_iplayer), but they didn't
reply.  Does anyone here know?

-- 
Jeremy Nicoll - my opinions are my own.