Knowledge

XER, XML & MPP Files

Project File Formats: MPP, MSPDI/XML, MPX

MPP vs MSPDI/XML vs MPX — what each can hold

Microsoft Project Set Baseline dialog. Set baseline to Baseline, Entire project.
Set Baseline is a command in an open MPP. MSPDI XML is a different file format. MPXJ does not write a real MPP.

MPP

Microsoft: "The standard file format for a project which uses the .mpp extension." Proprietary OLE compound document, versioned by Project year.

Microsoft (current desktop):

  • Project 2010 / 2013 / 2016 share one format (a 2016 file opens in 2010/2013).
  • Can open/save Project 2007 format.
  • Can open 2000–2003 format; cannot save to it.
  • Cannot open or save Project 98.

MPP holds the full desktop project including views, tables, filters, bar styles. MPXJ can read MPP. MPXJ cannot write a real MPP. See convert/mpxj.md.

MSPDI (Microsoft Project Data Interchange, XML)

Microsoft: XML "can be used to interchange project data between Project and other programs." Documented schema on Microsoft Learn (tasks, resources, assignments, calendars, constraints, extended attributes).

MPXJ: "Since Microsoft Project 2002, Microsoft Project has been able to read and write an XML-based data interchange format called MSPDI."

This is the format we generate. It holds schedule data (tasks, links, calendars, constraints, work). It does not hold MPP view/presentation. MPXJ FAQ: none of the supported output formats contain view appearance.

MPX

Legacy Microsoft Project Exchange text format (Project 98 era). Microsoft: current Project desktop cannot open or save MPX. MPXJ can still read and write MPX. Localized MPX files use localized strings; English Project cannot read a localized MPX and vice versa.

Do not emit MPX for a modern Project user.

What current desktop will not open

Microsoft: Project 98, MPX, MPD, MDB, ODBC — cannot open or save.

Sources

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