Lists are represented very unfriendly in JSON replies. I would rather say that it is a bug.

Let us take task list as example, for example its part taskseries[i].task, which can have multiple occurences. If there are several occurences, its JSON result is in the format like

task
0
id: 35956223
due: 2008-12-06T23:00:00Z
has_due_time: 0
added: 2008-11-02T21:38:00Z
completed:
deleted:
priority: N
postponed: 0
estimate:
1
id: 35946758
due: 2008-11-01T23:00:00Z
has_due_time: 0
added: 2008-11-02T18:20:36Z
completed: 2008-11-02T21:38:00Z
deleted:
priority: N
postponed: 0
estimate:

However, if there is only one occurence, the format is

task
id: 35950030
due: 2008-11-15T23:00:00Z
has_due_time: 0
added: 2008-11-02T19:38:13Z
completed:
deleted:
priority: N
postponed: 0
estimate:

And this seems to be true for every single list in API results.

This means that the API user need to take care of this inconsistent representation everywhere. JSON result would be definitely more logical and processable if the single occurence would be represented like

task
0
id: 35956223
due: 2008-12-06T23:00:00Z
has_due_time: 0
added: 2008-11-02T21:38:00Z
completed:
deleted:
priority: N
postponed: 0
estimate: