A key asset of every practitioner of Getting Things Done (GTD) is her or his set of Next-Action (NA) Lists.

NAs are not dumped into a single ToDo list. Instead, each list is focused on a given context that allows you to complete the action. According to David Allen, a context describes the tool, location or person that is required to be able to complete an action.

@Home, @Office, @Phone are typical examples. When you arrange your NAs like that, you're obviously in a much better position as soon as you're in the respective context and want to know what you should do now.

But what exactly is a context, and what isn't?

Types of contexts and how to handle them

During my last weekly review, I've had a look at my NA lists and I wondered what types of contexts exist. Here's my list, please add a comment below to share additional types. Here we go:

1. People
   Examples: @Joe, @Mom and dad.
   Usually, this list takes the form of an agenda. Such lists are real life savers when your stress level is extremely high and you need to fly by autopilot.
2. Roles and service providers
   Examples: @Boss, @M.D., @Delivery/FedEx/UPS.
   Better distinguish between roles and individual people, even when you're at very good terms with them.
3. Locations
   Examples: @Desk, @Home, @Office, @Club, @San Diego Office.
   Places you stay at on a regular base.
4. Errands
   Examples: @Walmart.
5. Recurring event agendas
   Examples: @Weekly sales meeting.
6. Recurring idle time spans
   Examples: @Morning coffee, @Gym, @Jogging, @Commuting.
   Please consider Leo Babauta's advice on establishing calming routines and keep some idle time spans free from any todos. Sometimes, idle isn't really idle.
7. Allocated time spans
   Examples: @Reading, @Creative.
   Christian Eriksson points at an allocation example and Keith Robinson presents a similar idea for creative work.
8. Required resources or tools
   Examples: @Online/Web, @PC-Offline/Mac anywhere, @Phone/Calls, @Email, Merlin Mann even lists: @Google
   It's not just the resource, but also the flow state when using it. Steve Pavlina criticizes GTD for requiring him to maintain lists like @Phone, saying he doesn't want to «scramble actions from different projects together». That's throwing out the baby with the water. GTD is not about staying focused on a single project, GTD is about avoiding task switching. When your projects look very similar to each other, batching similar tasks avoids task switching; completing a single project under such circumstances would involve more switching among more diverse task types.
   [2007-09-05 Update: See this posting on the David Allen forum for anecdotal evidence.]
9. Habits
   Example: @Home.2Minutes.
   Chores and resolutions. Since it is hard to remember especially the minor ones, a list comes in handy.

Fake context types

1. Actions or Projects
   Unfortunately, Merlin Mann initially listed actions like brainstorm, decide, print, read, write, schedule, refactor under «actionable contexts». David Allen doesn't call them contexts; when he talks about reading, e.g., he doesn't even mean an allocated time span (see above), but just a folder containing the actual items (articles, memos, printed emails, whatever). A better option than calling the above contexts would be to ask yourself: in which context will I be able to brainstorm, decide, print, read, etc. The answers will be different for each type of action. You won't bring your complete reading folder everyhere, that's a myth. And you can't just «print» everywhere: your boss isn't pleased when you print your private stuff in the office; your friends may not have any mac-compatible software installed on their Windows machines; your parent's printer may not be a color inkjet. So there is a hidden context here.
2. Singular Events (opposed to: recurring events that have agendas, see above)
   «@Vacation in Greece» isn't a context, but a project. Put this on your project list and fill the next actions into the appropriate context lists or calendar pages. Your calendar and your errand list are valid in Greece, too…
3. Available time or energy levels
   Brian Kei Tanaka talks about short-time and long-time contexts equating short-time with a low energy level requirement: @Computer, short However, on the whole there are three factors that guide your choice of the next task to be completed: priority, energy level, available time. Turn one of them into a context and the other ones become second-class citizens of your reliable system. E.g., you may have plenty of energy left - will you tackle the longer tasks only and miss the important short ones on the other list? If you want to track such factors, it's better to add extra columns to @Computer, to hold your assessment of priority, required energy level, and required time.
4. Priorities
   Using contexts like @Urgent, @Important, or @A/@B/@C is an indicator that you've fallen back to traditional «time management» methods. It's not helpful to know that a next action is urgent if you can't act upon it where you are right now.
5. Invariant time spans
   What about using @Today, @AM, @PM and the likes? Bobby Sullivan seems to suggest an Outlook category like Today was also a GTD context. While his category hack is great for planning the daily workload, his assumption isn't correct. Be sure not to confuse invariant time spans with contexts: planning to complete a next action within an invariant time span does not turn that time span into a context. It's easy to see that you're not always in the same place at the same time of day.

If you tend to have a lot of these, read Merlin Mann's advice on slashing contexts; it reminds me of the software development danger that Bertrand Meyer called Taxomania (IT-specific link, beware), the excessive desire of building classification trees for the only purpose of classifying.

The intersection problem and how to solve it

When you see two or more context candidates for a next action, you've bumped into the intersection problem. Hardly any given set of contexts is free of intersections. For instance, assume you may make phone calls @Home, @Phone or @Office. To which list will you add, e.g. «Call Jim and arrange for meeting next Thu»?

There are various ways to tackle that problem. Here's my list of strategies in the preferred order of application:

1. Favor the generic context over the specific one
   Add «Call Jim and arrange for meeting next Thu» to @Phone, because that category is more generic and you need to check @Phone when you're @Home and @Office anyway. If you haven't got @Phone yet, create that list now.
   Obviously, this does not work if your company does not permit non-business calls from your workplace.
2. Merge contexts
   if your boss does not like when you make private calls from your workplace, and you don't have a cell phone anyway, then cancel the @Phone list and merge its content («Call Jim and arrange for meeting next Thu») into the @Home list.
3. Favor frequent contexts over rare ones
   Choose the context you're in more often. Is that @Home, @Phone or @Office? Adding «Call Jim and arrange for meeting next Thu» to it increases the chances that you'll get to see this task earlier. Of course, seeing does not mean completing.
4. Favor permanent contexts over temporary ones
   Assume you're a freelancer who mostly works at the customer's site, in an office that is temporarily yours. «Call Jim and arrange for meeting next Thu» goes into @Home, because that saves you the transfer form @Office to @Home when your contract ends.

What are your suggestions for dealing with contexts? Let me know in the comments, below.