But they remained upset with IBM for by the International Organization for Standardization (ISO). The two co-authored an open letter this week entitled " ," that pointed fingers of blame at IBM.

"The open letter is an effort to clearly articulate what Microsoft is trying to do," Robertson said. It is important to shine a light on what IBM is doing to block Open XML and block choice, he added.

In response, an IBM representative pointed to the , which states there is "significant commercial opposition" to Microsoft's electronic document proposal.

Microsoft made a "bad bet " that ODF would fail in the marketplace, the blog stated.