For more information on frequently used technical terms, see also the XMM Glossary.
| Acronym | Explanation |
|---|---|
| AO | Announcement of Opportunity (AO-1) |
| AMS | Archive Management Subsystem |
| AXAF | Advanced X-ray Astrophysics Facility |
| CCD | Charge Coupled Device |
| Co-I | Co-Investigator |
| DEC | Declination,  (J2000) |
| EPIC | European Photon Imaging Camera |
| ESOC | European Space Operations Centre |
| ESTEC | European Space Research and Technology Centre |
| FAQ | Frequently Asked Question |
| FITS | Flexible Image Transport System |
| FOV | Field Of View |
| FWHM | Full Width at Half Maximum |
| GO | Guest Observer |
| GSFC | Goddard Space Flight Center |
| GT(O) | Guaranteed Time (Observer) |
| GUI | Graphical User Interface |
| HEASARC | (NASA) High Energy Astrophysics Science Archive Research Center |
| HEW | Half Energy Width |
| HER | RGS High Event Rate (selectable mode) |
| HTR | High Time Resolution (mode of the RGS) |
| LSF | Line-Spread Function |
| MOC | XMM Mission Operation Centre |
| MOS | Metal Oxide Semi-conductor |
| ODF | Observation Data File |
| OM | Optical Monitor |
| OTAC | Observatory Time Allocation Committee |
| QLA | Quick Look Analysis (software) |
| PHS | Proposal Handling Subsystem |
| PI | Principal Investigator |
| PIMMS | Portable, Interactive Multi-Mission Simulator |
| PSF | Point-Spread Function |
| PV | Performance Verification |
| RA | Right Ascension,  (J2000) |
| RFC | RGS Focal Camera |
| RFS | Refreshed Frame Store mode of EPIC MOS |
| RGA | Reflection Grating Assembly (of the RGS) |
| RGS | Reflection Grating Spectrometer |
| XRPS | Remote Proposal Submission |
| SAS | Science Analysis Subsystem |
| SER | RGS Split Event Reconstruction (selectable mode) |
| SES | RGS Single Event Selection (selectable mode) |
| SOC | XMM Science Operations Centre |
| SSC | Survey Science Centre |
| TBC | To Be Confirmed |
| TBD | To Be Determined |
| TOC | Table of Contents |
| ToO | Target of Opportunity |
| UHB | XMM Users' Handbook |
| URL | Unique Resource Location |
| W90 | 90% Energy Width |
| WWW | World Wide Web |
| XMM | X-ray Multi-Mirror Mission |
| XRPS | XMM Remote Proposal Submission |