GP4 is an image extension included in the CALS group of formats. CALS (Continuous Acquisition and Life-cycle Support) represents an initiative undertaken by the Department of Defence in the United States in the 1980s, with the aim of creating a standard for storing and linking military data. Similar formats include CG4, CAL and CALS. Most formats that are part of the CALS group are currently considered rare and obsolete.
JPEG JPG PNG GIF TIFF TIF BMP ICO EMF WMF AI PDF EPS PS EPI WEBP WEBPLL JP2 PCX TGA DWG DWF DXF DGN WMZ CGM DRW GBR PCT MIF PLT PCL SVG WPG CIN DCX DIS HRU MTV PRC RAD PIC RLA QRT SGI XBM XPM SWF CAL PSD JXR BPG APNG DDS SVGZ CG4 FLIF