while obsessively walking the Wales Coat Path, I saw a lady wearing a T shirt which said:=
'I have CDO, its like OCD, but with the letters neatly arranged in alphabetical order'
Just completed the Trent and Mersey canal walk.

From a 2016 Amazon review by one Willie Taylor of Julie Welch's 'Out on Your Feet' (Arum Press 2009):

"This was a weird book. I certainly didn't dislike it, but it wasn't what I expected. [...] I wanted to know more about the intricacies of the [annual Hundred] walks. What to wear, what to take with you etc. There was actually very little of that. I also thought that the sketches made the Long Distance Walkers Association sound very Middle England, a bit like a Women's Institute [WI] for the OCD [Obsessive Compulsive Disorder[ed]]".

God to see it's still being discovered ...

(From the evidence of the other Amazon reviews, Julie's book has encouraged at least one other reader to start - and I think is still - doing Hundreds.)

Iain