| Value | Meaning |
|---|---|
| Header"IHDR" | Standard, for header, before image data |
| Palette"PLTE" | Standard, for palette, after header and before image data |
| Data"IDAT" | Standard, for image data |
| End"IEND" | Standard, file end marker |
| Background"bKGD" | Background color |
| Chromaticies"cHRM" | Primary chromaticities and white point |
| Gamma"gAMA" | Image gamma |
| Histogram"hIST" | Image histogram |
| PixDim"pHYs" | Physical pixel dimensions |
| SignifBits"sBIT" | Significant bits |
| TextData"tEXt" | Textual data |
| Time"tIME" | Last modification date |
| Transparency"tRNS" | Transparency |
| CompTextData"zTXt" | Compressed textual data |
| IntTextData"iTXt" | International textual data |
| AnimationControl"acTL" | Animation control chunk |
| FrameControl"fcTL" | Frame control chunk |
| FrameData"fDAT" | Frame data |
Chunk initializer IDs.