Related to Use a more standard flavor of markdown
A common representation of TODO/DONE in Github Flavored Markdown is [ ] and [x] (or [X]), it doesn’t include DOING but it is very frequently used.
It would be great if customisation of TODO keywords allowed for this syntax. Maybe ongoing tasks could be written as [o] ? Or for GFM (Github Flavored Markdown) compatibility it could be - [ ] DOING.