PRC (Palm OS)

PRC (Palm Resource Code) is a container format for code databases in Palm OS, Garnet OS and Access Linux Platform. Its structure is similar to PDB databases.^[1] Usually, a PRC file is a flat representation of a Palm OS application that is stored as forked database^{[clarification needed]} on the PDA.

PRC files are also used by the Mobipocket e-book-reader (here sometimes referred to as MOBI format^[2]). The AZW format of Amazon's Kindle reading device is in turn a DRM-restricted form of the Mobipocket format.

On Palm OS, PRC files are used for applications, localized resources (overlays) and shared libraries.^[1]

Structure of PRC file

In its essence, a PRC file is similar to a classic Mac OS application. It contains a PRC header, PRC resource headers and PRC resources.^[3]

PRC Header

PRC Resource Header

PRC Resources

PRC Header

The PRC header is located at the beginning of the file and contains meta-information on the file:^[3]

Offset	Name	Type	Size
0x00	name	char	32 Bytes
0x20	flags	integer	2 Bytes
0x22	version	integer	2 Bytes
0x24	creation time	32bit integer - PDB Datetime	4 Bytes
0x28	modification time	32bit integer - PDB Datetime	4 Bytes
0x2c	backup time	32bit integer - PDB Datetime	4 Bytes
0x30	mod_num	integer	4 Bytes
0x34	app_info	integer	4 Bytes
0x38	sort_info	integer	4 Bytes
0x3c	type	integer	4 Bytes
0x40	creator	integer	4 Bytes
0x44	unique_id_seed	integer	4 Bytes
0x48	next_record_list	integer	4 Bytes
0x4c	num_records	integer	2 Bytes

PRC Resource Header

For every resource (specified by num_records), there is a resource header containing:^[3]

name	type	notes	size
name	char	Name of the resource	4 bytes
ID	integer	ID number of the resource	2 bytes
offset	integer	Pointer to resource data	4 bytes

PRC Resources

Every application contains al least a Code #0 resource with size information and jump tables, a Code #1 resource with executable code and data resources containing pre-initialized values of global variables in compressed form.^[3] Other resources that may be contained are forms, form objects, alerts and multimedia data, e. g. images and sounds.