In a nutshell, a GZIP file consists of a header followed by compressed data (using the “deflate” compression algorithm), followed by a trailer. The GZIP file format is specified here: GZIP file format.
The Chilkat GZip component’s Compress* and Uncompress* methods read and write the GZIP file format. Data passed to an Uncompress* method should contain the header, compressed data, and trailer. The output of a Compress* method is a header, followed by compressed data, followed by a trailer.
The Chilkat Gzip component also provides two methods for inflating and deflating just the compressed data part of a GZip file. These methods are named InflateStringENC and DeflateStringENC. It is not correct to pass data that includes the GZIP header and trailer to InflateStringENC. Likewise, the DeflateStringENC method does not produce a GZIP file — it simply compresses data using the deflate compression algorithm and returns the resultant compressed data.