Such work is common before a merger and suggests that acquisition talks between Sun and IBM, which were reported earlier this week but have not been confirmed by the companies, are still under way. Examining the documents could take a number of days, the Journal said.

The work being done includes an examination of Sun's software license terms to see if any of them conflict with IBM's business practices, the newspaper reported. Sun offers most of its software, including its Solaris OS, MySQL database and Java programming language, under a variety of open-source licenses.

News of the supposed merger talks was broken by the Journal overnight on Tuesday, though Sun and IBM have not confirmed nor denied any discussions. IBM would pay between US$6.5 billion and $8 billion to buy the company, the Journal said Friday.

Observers have been puzzling over whether IBM is interested in Sun for its hardware or its software assets. IBM would gain some of Sun's large corporate customers and widen its lead in the enterprise server market, where it was just ahead of Hewlett-Packard last year, according to IDC.

There would also be significant overlap between the companies' product lines, however. Both have a Unix server OS, a RISC chip architecture, at least one enterprise database and a whole line of middleware. Any deal would create uncertainty for customers as to which products IBM would continue to develop and support.