Update large CakePHP model, but *don't* touch certain fields?

[BruiserDiamonds]

Using CakePHP 1.3I have a fairly large model in CakePHP, and I'd like to have some hidden elements on the form page to (manually) compare/validate against before saving, but when doing a \[code\]saveAll()\[/code\] (with validation), I don't want these fields present (essentially to avoid them being updated). What's the proper way to handle this? Remove them from \[code\]$this->data\[/code\] before handing that to \[code\]saveAll()\[/code\]?