In my article on GTD contexts, I mentioned the need to decide on your own tags. These should be chosen from the ones your mind includes when it creates a task.
Here is an excerpt from a table of my book, Perfect Time-Based Productivity, with some examples.
I also offered the following examples in the original article.
Example #1 – Flow State – Hi / Med / Lo / n/a
Example #2 – Cash – Free, $1-500, $501-1000, $1001-5000, $5001+
Example #3 – Manpower – Solo, Partner, Trio, Four +
Example #4 – Energy/Strength – Hi / Med / Lo
Example #5 – Mentality – Work, Vacation, Holiday, Weekend, Evening
Example #6 – Profitability – Hi / Med / Lo
As I mentioned in the article, the possibilities are endless, but I recommend that you only pick the tag(s) which represent the scarcest attributes. These vary by individual, and require some introspection to unearth.