one thing i'd love to see it expand is contexts.
From my viewpoint an task can have 4 types of contexts 'what, when, who and where' and additionally others.
It would be great if the spec expanded to support more context prefixes
like # or & ..
Currently i use @& for who contexts , @@ for where contexts, + / @ for what contexts ..
Having more context prefixes can speed up quick task additions using auto suggest. With suggests filtering on prefixes.
@-personpattern, personally because then I do do
todo.sh ls @-to find all the tasks that involve people