Armory strives to be as open and easy as possible, for other developers to interact with it. For instance, one shortcoming of the Satoshi client (www.bitcoin.org) for developers is that all wallet data is stored using the BSD database engine. As a developer that might want to also utilize the wallet files, it can be difficult to find your private key data, and risk corrupting the database when it is modified.
On the other hand, Armory uses a remarkably simple wallet file format, that can be read and modified by any developer who has the binary map for it (included below). The format includes checksums for data integrity of critical information, and Armory uses the checksums to autocorrect 1-byte HDD errors (this does happen!). Armory also has a special set of functions for appending/updating to the file that guarantees if the wallet becomes corrupted, it will be automatically detected and recovered.
While other clients don’t need to implement the error-correction and corruption-resistance, it is important for the format to be made public so that other client developers can either share the file format, or write conversion tools. The format is shown below.
Note: It should be kept in mind that checksums are not best way to handle error-correction. Something like Reed-Solomon would be much more effective, but add extra complexity to something that already works. Simplicity is preferred!