Phar File Format
Phar manifest file entry definition
What makes a phar a phar and not a tar or a zip?
PHP Manual

## Global Phar bitmapped flags

Here are the bitmapped flags currently recognized by the Phar extension for the global Phar flat bitmap:

Bitmap values recognized
Value | Description
--- | ---
0x00010000 | If set, this Phar contains a verification signature
0x00001000 | If set, this Phar contains at least 1 file that is compressed with zlib compression
0x00002000 | If set, this Phar contains at least 1 file that is compressed with bzip compression