After the World Motor Sport Council meeting late in June, when peace with the rebel FOTA teams was declared, the FIA said the "rules for 2010 onwards will be the 2009 regulations".
But shortly afterwards, FIA president Mosley said in an interview that amending the published regulations actually depended on FOTA striking "an agreement with the Williams and Force India teams and the three new teams".
The 69-year-old Briton has now clarified this point in writing, suggesting that the five teams outside the FOTA alliance can actually block the scrapping of the budget cap due to Article 66 of the International Sporting Code.
Mosley said "no change can be made to the published regulations without the agreement of all confirmed entrants".
In theory, this could be a major problem for FOTA, given not only that the five non-FOTA teams signed up for the budget cap, but that some of the new entrants may be unable to join the 2010 grid without the radical cost reductions.
We reported on Tuesday that all thirteen 2010 teams will meet for technical discussions at the Nurburgring on Wednesday.