Open a Microsoft Project XML file

A Project .xml, also called MSPDI, is the same plan an .mpp holds, written out as text. Every value is there, but the structure is implied: dependencies are identifiers pointing at identifiers, the outline is a level number per task, durations read PT40H0M0S. Here that is rebuilt into a Gantt chart, with nothing recalculated on the way in.

It opens in a text editor, and that is exactly the problem

This is the format people are most confident they can handle themselves, because the first attempt goes so well. Open the file in Notepad and there it is: task names in plain sight, dates you can read, a tag around every value. Nothing is encrypted, nothing is binary, nothing is hiding.

Then you try to answer a question with it. How long is that task? The file says PT40H0M0S. What does it wait for? The file says <PredecessorUID>24</PredecessorUID>, so you scroll back through a few thousand lines looking for the task whose identifier is 24, and when you find it you learn that it in turn waits for 19 and 21. Where does this task sit in the plan? There is no tree in the file at all - only an <OutlineLevel> number on each task, from which the hierarchy has to be rebuilt in your head, in order, without losing your place.

A schedule is a structure, and the text is only its raw material. Reading the values one at a time is not the same as reading the plan, and no amount of patience closes that gap.

Why you were sent one

Someone asked for a file you could open, and this is what Microsoft Project offers. It is the export people reach for precisely when the recipient has no Project - and also the format other scheduling tools import, so it is what travels between ecosystems. Primavera P6 is the exception: it has an exchange format of its own, the .xer.

The schema has a name, MSPDI, which is worth knowing only because you will meet it in documentation and in the export dialog. It describes the same file: one XML document holding tasks, assignments, resources, calendars and the links between them.

What the chart shows you

The same four things anyone wants from someone else's plan, without the scrolling.

• The shape of the schedule. Phases fold and unfold, so you can collapse the parts that are not yours and look at what is.
• The critical path, marked as the file records it, so you can see which chain actually drives the finish date.
• What is already late, because every task is set against today's date rather than against the day the file was made.
• What any task waits for - click it and its predecessors and successors are listed by name, with the link type and any lag, instead of by number.

This format survives the trip better than most

Worth saying plainly, because it is not true of every format. A Project XML writes its dates, durations and progress out as explicit values rather than leaving them to be worked out again by whatever opens it. So what the chart shows is what the file says - task by task, date by date, and percentage by percentage, with nothing recalculated on the way in.

What still stays behind is what the format keeps for Microsoft Project's own use rather than for a reader:

• Slack and float figures. You see which tasks are critical, not how many days of float the others have.
• Costs, rates and resource levelling. Resource names and assignments come across; money does not.
• Custom fields, flags and outline codes that a planner defined for their own reporting.
• More than one baseline, and any comparison between them.
• Views, tables, filters and groupings saved inside the plan.

And it reads one way. Nothing here writes an .xml back, and the file you drop is never altered.

XML or .mpp - does it matter which they send you?

Not here; both open. It is worth knowing the difference anyway, because you may get to ask.

An .mpp is Microsoft's own binary format - compact, and completely unreadable without software that understands it. An .xml is the same plan written out as text: several times larger on disk, openable in any editor, and, as above, still not readable in any useful sense. The choice changes the file size and nothing about whether you can make sense of it unaided.

If someone asks which to send, ask for whichever they already have. If they are exporting specially, XML is the safer bet - it is a documented format, and it is what other tools import.

Common questions

What is MSPDI?

The name of the XML schema Microsoft Project uses when it saves a plan as .xml. A file described as MSPDI and a Project .xml file are the same thing.

Is a Project .xml the same as an .mpp?

The same plan, written differently. The .mpp is binary and compact; the .xml is text and larger. Both open here, and both show the same chart.

Why can I see the data in a text editor but not read the plan?

Because the structure is implied rather than written. Dependencies are stored as identifiers pointing at other identifiers, the outline is a level number on each task, and durations are written in a machine format such as PT40H0M0S. The values are all there; the shape they make is not.

Is my file stored anywhere?

No. It is read in memory and gone as soon as the chart is drawn. An account exists only if you want plans kept so you can come back to them or share a link.

Can I turn it into a spreadsheet?

Yes. The same read produces an .xlsx - one row per task, with real dates, durations, resources and predecessors, and a filter already switched on.