This function returns a compressed version of the input data compatible with the output of the gzip program.
For more information on the GZIP file format, see the document: GZIP file format specification version 4.3 (RFC 1952).
The data to encode.
The level of compression. Can be given as 0 for no compression up to 9 for maximum compression. If not given, the default compression level will be the default compression level of the zlib library.
The encoding mode. Can be FORCE_GZIP (the default) or FORCE_DEFLATE.
If you use FORCE_DEFLATE, you get a standard zlib deflated string (inclusive zlib headers) after the gzip file header but without the trailing crc32 checksum.
The resulting data contains the appropriate headers and data structure to make a standard .gz file, e.g.: