When rendering with the Write node, Nuke lets you write out metadata into the following file formats: .exr, .cin, .dpx, and .jpg. You cannot write out metadata into any other formats.
When rendering metadata into an .exr file, you can use the metadata dropdown menu in the Write node controls to specify what to write out:
• no metadata - Do not write out any metadata, except for metadata that fills required header fields (for example, file name and bbox).
• default metadata - Write out the time code, edge code, frame rate, and exposure.
• default metadata and exr/* - Write out the time code, edge code, frame rate, exposure, and anything in exr/.
• all metadata except input/* - Write out all metadata, except anything in input/.
• all metadata - Write out all metadata.
When rendering any other file format than .exr, Nuke writes whatever metadata the file format header is known to support. Therefore, what is written out varies according to the file format.