HST data use the 'ipppssoot' file naming convention. Each letter is mapped as follows:
i : instrument identifier, will be one of:
| E = Engineering data, |
| F = Fine Guidance Sensors (FGS), |
| I = Wide Field Camera 3 (WFP3), |
| J = Advanced Camera for Surveys (ACS), |
| L = Cosmic Origins Spectrograph (COS), |
| N = Near Infrared Camera and Multi-Object Spectrograph (NICMOS), |
| O = Space Telescope Imaging Spectrograph (STIS), |
| S = Engineering subset data, |
| T = Guide Star position data, |
| U = Wide Field/Planetary Camera-2 (WFPC2), |
| V = High Speed Photometer (HSP), |
| W = Wide Field/Planetary Camera (WFPC), |
| X = Faint Object Camera (FOC), |
| Y = Faint Object Spectrograph (FOS), |
| Z = Goddard High Resolution Spectrograph (HRS) |
ppp : Program ID; can be any combination of 3 letters or numbers. There is a unique association between program ID and proposal ID (generally equivalent to the 5-digit HST phase-2 ID),
ss : Observation set ID (generally equivalent to the HST phase-2 visit number); any combination of 2 letters or numbers.
oo : Observation ID (generally unique for each exposure); any combination of 2 letters or numbers.
t : Source of transmission or association product number, one of the following letters or numbers 0-8:
| B = "B-associations" generated by CADC and ST-ECF for WFPC2, |
| M = Merged real time and tape recorded, |
| N = Retransmitted merged real time and tape recorded, |
| O = Retransmitted real time (letter 'O’), |
| P = Retransmitted tape recorded, |
| Q = Solid-state recorder |
| R = Real time (not recorded), |
| S = Retransmitted solid-state recorder, |
| T = Tape recorded, |
| 0 = Primary association product (number zero), |
| 1-8 = ACS, COS, NICMOS, or WFC3 association sub-product |
HST data use a number of suffix rules after the 'ipppssoot' name.
Uncalibrated:
| Suffix | Description | Used with the following Instrument(s) |
| _raw | Raw data | WFC3, ACS, NICMOS, STIS |
| _tag | Raw timetag data | STIS |
| _lrc | Local rate check image (BOP) | STIS |
| _wav | Wavecal | STIS |
| _wsp | Wavecal support file | STIS |
| _asn | Association file | WFC3, ACS, COS, NICMOS, STIS |
| _spt | Telescope, telemetry, engineering | WFC3, ACS, COS, NICMOS, STIS |
| _trl | Trailer, processing log | WFC3, ACS, COS, NICMOS, STIS |
| _rawacq | Raw data | COS |
| .d0h/.d0d | Science data image | FOS, GHRS, WFPC1, WFPC2, FOC |
| .q0h/.q0d | Science data quality | FOS, GHRS, WFPC1, WFPC2, FOC |
Calibrated:
| Suffix | Description | Used with the following Instrument(s) |
| _flt | Calibrated, flat-fielded exposure | WFC3, ACS, STIS |
| _crj | Calibrated, CR-rejected, combined | WFC3, ACS, STIS/CCD |
| _drz | Calibrated, geometrically-corrected, dither-combined | WFC3 ACS |
| _fltsum | Calibrated, flat-field for images | COS |
| _x1dsum | Calibrated, combined 1D extracted for spectra | COS |
| _x1d | Calibrated 1D spectra from exposures | STIS |
| _x2d | Calibrated 2Dspectra/images from exposures | STIS |
| _sx1 | Calibrated 1D spectra from combined exposures | STIS |
| _sx2 | Calibrated 2D spectra/images from combined exposures | STIS |
| _cal | Calibrated exposure | NICMOS |
| _mos | Calibrated, combined image | NICMOS |
| _sfl | Summed, flat-fields image | STIS/MAMA |
| .c0h/.c0d | Calibrated wavelengths | FOS, GHRS |
| .c1h/.c1d | Calibrated fluxes | FOS, GHRS |
| .cqh/cqd | Calibrated science data quality | FOS, GHRS |
| .c0h/.c0d | Calibrated science data | WFPC1, WFPC2, FOC |
| .q0h/.q0d | Calibrated science data quality | WFPC1, WFPC2, FOC |
| i=F (FGS) |
| ppp=05Q |
| ss=74 |
| oo=07 |
| t=M (Merged) |
Additional examples and information can be found in the HST Handbook and here.