Why are two <cr> characters required when executing this highlighting toggle command?

Question

I use this keymapping toggle to highlighting on and off, but when I originally found it, the author did not list two <cr> at the end of the command. I found that if I didn't have two <cr> there, then I was required to press Return after my keymapping. Why? ... because now that I can get the macro (wrong term?) to execute, my cursor advances to the next line after executing the mapping.

highlight OverLength ctermbg=gray
match OverLength /\%81v.\+/
let OLstate = 1
nnoremap oi : if (OLstate == 0) \| match OverLength /%81v.\+/ \| else \| match OverLength /%9999v/ \| endif \| let OLstate = 1 - OLstate <cr> <cr>

Answer 1

I think you want

: ... endif <cr> :let OLstate = 1 - OLstate <cr>

instead of

: ... endif \| let OLstate = 1 - OLstate <cr> 

That is, <cr> after the endif, a : before let and <cr> after the let statement. There are two commands.

I'm using vim 7.4, plain vanilla, no .vimrc, no plugins.