I do the same for my personal notes. Something like (the actual contents differ because I take notes in my native tongue): if exists("b:current_syntax")

I do the same for my personal notes. Something like (the actual contents differ because I take notes in my native tongue): if exists("b:current_syntax") finish endif syn match diaryHashtag "\w\@<!#[A-Za-z]\+" syn match diaryInlineCode "`[^`]\+`" syn match diaryLineMarker "^[ \t]*\%([0-9]\+\.\|[*-]\)\S\@!" syn match diaryInlineMarker "=>\|\S\@<!(\?\%(i\{1,3}\|iv\|vi\{0,3}\|ix\|x\))\S\@!" syn match diaryInlineDate "\<\%(today\|yesterday\|tomorrow\|\%(\%(next\|last\)\s\)\=\%(mon\|tue\|wed\|thu\|fri\|sat\|sun\)\|20\d\d-\d\d\%(-\d\d\)\=\)" syn match diaryInlineTime "\<\%(\d\d\=:\d\d\|morning\|afternoon\|night\)" hi default link diaryHashtag String hi default link diaryInlineCode Delimiter hi default link diaryLineMarker Statement hi default link diaryInlineMarker Statement hi default link diaryInlineDate Comment hi default link diaryInlineTime Comment let b:current_syntax = 'diary' But this system is entirely unusable for longer and potentially public writings.