"Interoperability tax" is a term worth introducing. It is, after all, why Microsoft faces a lot of scrutiny in Europe. Applications and platforms need to be able to communicate owing to some standard protocols. A startup should not need to apply for a mortgage only to be allowed to communicate with another piece of software. The recent claims made by Microsoft complicate things even further, as the following article explains.

Microsoft's bold patent claims against Linux could complicate the company's efforts to get along better with the open-source community and develop more interoperable products.

Essentially, Microsoft wants money for interoperability. The nerve of this can only be tolerated in a world where lockin is a privilege, not a dirty little trick. Have a look at the following. Not only might Microsoft deny file/printer access from other platforms, but virtualisation becomes a concern as well.

The company [Microsoft] is working with Novell to tie the Viridian and XenSource hypercall APIs, but don't hold your breath waiting for interoperability with other Linux vendors.

He also stated Microsoft is working closely with Novell to map its Viridian hypercall API with the XenSource hypercall API, in order to facilitate interoperability. He also implied recent developments by other unnamed Linux engineers and vendors may be making it difficult for Viridian to offer similar interoperability with other builds.

They still refuse to embrace open APIs and want to license proprietary technology instead, for lockin and 'innovation tax'. This could be another trick for pressusing customers to embrace 'taxable' Linux distributions, such as SUSE.