Microsoft Project Exchange file (.mpx) is an ASCII file format for transferring of project information between Microsoft Project (MSP) and other applications that support the MPX file format such as Primavera Project Planner, Sciforma and Timerline Precision Estimating.
Learn more about this file format here
GroupDocs.Viewer (in GroupDocs.Viewer.dll) Version: 20.9
public static readonly FileType MPX
Public Shared ReadOnly MPX As FileType
static initonly FileType^ MPX