After you uncompress a GZIP feed file, you can see that the contents are UTF-8 encoded and that each file contains a header row. The feed schema indicates the field delimiter, which is a tab.
If any of the following characters occur in the source data, they are escaped with a backslash:
tab (U+0009). Becomes a literal string \t
newline (U+000A). Becomes a literal string \n
backslash (U+005C). Becomes a literal string \\