For v2 .ofocus file format, please check the 2.0 branch.
This document is written by reverse engineering an Omnifocus 1.10 .ofocus file.
The .ofocus file is basically a directory with a set of .zip files.
Each .zip file contains a contents.xml file, which is a transaction (a set of data) in XML format.
There is a master file named 00000000000000={randomId}+{randomId}.zip and multiple files named {date in GMT}={randomID}+{randomID}.zip which are transactions files that apply over the master file. The randomId values have the same format as the random ids used within the file (see id in the Formats section).
To build the history, one will start with the master file and read the chain of transactions files, something that will look like the following:
00000000000000={randomId}+{A}.zip (master file)
{date in GMT}={A}+{B}.zip (transaction file 1)
{date in GMT}={B}+{C}.zip (transaction file 2)
{date in GMT}={C}+{D}.zip (transaction file 3)
...
{date in GMT}={Y}+{Z}.zip (transaction file n)
Whenever you sync with the server, a file with the format {date in GMT}={X}+{Y}+{Z}.zip, where X is the randomId of the oldest transaction file and Y is the randomId of the youngest transaction file, will be generated. This file does not contain any transaction in itself and only serves to indicate the junction of two disjoint history branches.
Oldest transaction file {date in GMT}={A}+{X}.zip
Youngest transaction file {date in GMT}={B}+{Y}.zip
Resulting transaction file
Because date in GMT of the oldest < date in GMT of the youngest,
{date in GMT}={X}+{Y}+{Z}.zip
Any transaction file generated next will henceforth be named {date in GMT}={Z}+{C}.zip, where Z is the randomId generated for the resulting transaction file.
My impression is that conflict resolution is simply handled by taking the latest change that occured to a task and consider it the source of truth. If both my iPhone and my Desktop have differences on a task status/name, the changes that will have been done last will be the one preserved, which makes sense in the context of time.
Omnifocus tracks clients by using files with the format {date in GMT}={randomId}.client on the synchronization server. Such files contain a plist with a dictionary in it with various properties of the client device such as the number of cpu, the OS version, an identifier of the Omnifocus client version used as well as one very important piece of information: an array of tailIdentifiers. As one can deduce from the name, it tracks the last synced transaction file, indicated by the second randomId of the transaction file's name.
Note that it is likely that you will see multiple client files for your device but with different date timestamp. When looking for the most up to date data, make sure to use the latest client file available.
Whenever Omnifocus realizes that all known clients are synchronized up to a certain transaction file, it is free to compress the transaction history back into the master file.
00000000000000={randomId}+{A}.zip (master file)
{date in GMT}={A}+{B}.zip (transaction file 1)
{date in GMT}={B}+{C}.zip (transaction file 2)
{date in GMT}={C}+{D}.zip (transaction file 3)
... Compression ...
00000000000000={randomId}+{D}.zip (master file, with transaction files 1, 2, 3 merged in)
The content of each contents.xml is as follow:
Legend (...) Attributes Optional
- omnifocus
- setting(id : id)
- added(order : unsigned int) : datetime
- modified : datetime
- plist(version : string) : string/xml
- context(id : id)
- added(order : unsigned int) : datetime
- modified : datetime
- name : string
- rank : signed int
- context(idref : id) - reference to parent context
- location(name : string, latitude : string, longitude : string) - latitute and longitude are signed decimal with a precision of 4
- folder(id : id)
- folder(idref : id) - reference to parent folder
- added : datetime
- modified : datetime
- name : string
- rank : signed int
- hidden : bool (not hidden by default)
- task(id : id) - has either a project or task child. A project child declares the project's properties while a task child declares the parent of the current task
- project - declares a project/single-action list
- folder(idref : id) - reference to parent folder
- last-review : datetime
- next-review : datetime
- review-interval : string (interval format)
- status : string (active, inactive, done, dropped) (if not specified, active by default)
- singleton : bool (if not specified, false by default) - indicate if the project is composed of single actions
- task(idref : id) - reference to parent task
- inbox - indicate if this task is part of the inbox
- note
- text (formatted as HTML)
- added(order : unsigned int) : datetime
- modified : datetime
- name : string
- rank : signed int (relative to parent task?)
- context(idref : id) - reference to context
- due : datetime
- start : datetime
- completed : datetime
- estimated-minutes : unsigned int
- flagged : bool
- order : string (parallel) (if not specified, sequential by default)
- repeat : string (interval format)
- repetition-rule : string (FREQ=MONTHLY, FREQ=WEEKLY;INTERVAL=4)
- repetition-method : string (fixed)
- project - declares a project/single-action list
- perspective(id : string/id) - either a predefined string (ProcessInbox, ProcessProjects, ProcessContexts, ProcessDueSoon, ProcessFlagged, ProcessReview, ProcessCompleted) or an id (see below)
- plist(version : string) : string/xml
- setting(id : id)
- omnifocus
- element(op="reference|add|update|delete") (not specifying an op = add)
A node with the property op="reference" is basically a copy of the referenced data included within the transaction (in case something were to happen to the original reference).
Any id referred to in the transaction file will be included as part of the transaction with an op="reference" attribute.
Ex.
<omnifocus>
<folder id="eaFlkIdRPr5" op="reference">
<added>2007-12-27T03:02:40.316Z</added>
<modified>2014-10-19T04:15:13.190Z</modified>
<name>Folder A</name>
<rank>-2112163194</rank>
</folder>
<folder id="jJK7jZbwOJB" op="reference">
<folder idref="eaFlkIdRPr5"/>
<added>2010-08-28T01:16:10.670Z</added>
<modified>2014-11-03T02:45:35.650Z</modified>
<name>Folder B (subfolder of A)</name>
<rank>1543503872</rank>
</folder>
<task id="mT0ok1Z2XE5" op="update">
<project>
<folder idref="jJK7jZbwOJB"/>
<last-review>2014-11-02T04:00:00.000Z</last-review>
<review-interval>@1w</review-interval>
</project>
<added>2014-11-03T02:45:35.650Z</added>
<modified>2014-11-03T02:45:37.852Z</modified>
<name>Task A (in Folder B)</name>
<rank>-2146024760</rank>
<order>parallel</order>
</task>
</omnifocus>Here, eaFlkIdRPr5 and jJK7jZbwOJB are referenced, that is, their data has been copied from the master file into the transaction file, simply so that the transaction file contains the appropriate references.
In this instance, task mT0ok1Z2XE5 references jJK7jZbwOJB (through <folder idref="jJK7jZbwOJB"/>), which "forces" the copy of folder jJK7jZbwOJB XML nodes with the addition of the op="reference" attribute. Since this folder references eaFlkIdRPr5, eaFlkIdRPr5 XML nodes will also be copied in the same way.
The id used as attribute is 11 characters long, in what appears to be base 64 (A-Za-z0-9\_\-).
The datetime is formatted according to ISO 8601 with precision to the milliseconds (2014-11-03T10:14:09.123Z).
Interval format is @periodduration (@1d, @1w, @1m, @1y)
The rank appears to be a global value shared by all data types. It is a signed integer (32 bits). There can be duplicate ranks. It would appear that ranks might only be unique within the same level of the hierarchy in order to provide ordering.
- omnifocus-viewer Omnifocus File Format
- Omnifocus forum, Omnifocus Data Storage thread part 1, part 2
- Omnifocus blog, OmniFocus: What We've Learned So Far (Engineering)