ZIM file format

The ZIM file format is based on the zeno file format. It starts with a header, which is described here:

Header

length in byte, all types are littlendian

Field Name	Type	Offset	Length	Description
rMagicNumber	integer	0	4	Magic number to recognise the file format, must be "1439867043"
rVersion	integer	4	4	wp2006=2, wp2007=3, ZIM=4, version of the file format for backwards compatibility
rCount	integer	8	4	total number of articles
	integer	12	4	deprecated
rIndexPos	integer	16	8	position of the article index
rIndexLen	integer	24	4	length of the article index
headerLen	integer	28	4	length of header (currently 60)
rIndexPtrPos	integer	32	8	position to the directory pointerlist
rIndexPtrLen	integer	40	4	length of directory pointerlist (always 4*rCount)
rMainPage	integer	44	4	article index of main page or 0xffff if no main page
rLayoutPage	integer	48	4	article index of layout page or 0xffff if no layout page
	integer	52	8	deprecated

Each article in the zim file has a directory entry. Since the directory entry has a variable size, we have a index pointerlist, which is a list of 4-byte offsets, which points to the directory entries.

Namespaces

Namespaces seperate different types of data stored in the ZIM File Format.

They can be distinguished by prepending the article namespace before the article name in the URL path, eg. http://localhost/A/Articlename.

Namespace	Description
-	template data
A	articles
I	images, files - see Image Handling
J	images, text - see Image Handling
U	categories, text - see Category Handling
V	categories, article list - see Category Handling
W	deprecated - see Zeno File Format
X	fulltext index
Y	deprecated - see Zeno File Format
Z	deprecated - see Zeno File Format