Microsoft Project support
OmniPlan is pretty good at working with Microsoft Project documents, and we're always working to make it even better, but there are a few things you should watch out for. Split tasks — Split tasks, which have a period of work, then stop, then start again at a later time, are not yet supported in OmniPlan. When importing a file with split tasks, each split task becomes one long task without any break in the middle.
Zero-length tasks — Microsoft Project tasks can have a duration of 0. In OmniPlan, though, a task with no duration is considered a milestone. When you import a Microsoft Project document, zero-duration tasks become milestones.
Unequal assignments — In Microsoft Project, if you assign more than one resource to a task you can specify how many hours of effort each assigned resource should contribute. If you don't specify, it assigns however much work to each that will complete the task earliest (taking schedule and resource assigned units into account). OmniPlan always uses that same automatic method. So, a task with effort hours specified for its resources may take a different amount of time in OmniPlan than it did in Microsoft Project.
Unicode characters — The Microsoft Project MPX format doesn't support the Unicode character encoding standard. If your project contains Unicode characters (say, some Chinese text for instance), you should use the more modern Microsoft Project XML format insead.