Most of the Sigma Camera Model's raw data, especially pre-Merrill, can exceed the theoretical ADC max value of 4095 by a lot - but without indicating any sensor saturation. For example, the SD14 is quite OK at values around 6,700 and indeed various numbers in the meta-data show nothing wrong with that.
So Sigma clearly does something to the ADC data before writing it as "raw" to the X3F file. That doesn't bother me too much - after all, the saturation level is easy enough to estimate from a simple over-exposed image.
But one irritating oddity to me is the DP2s compact model.
According to RawDigger, this camera saturates at about 2,400 - much less than the theoretical 4,095. As far as know the camera has 12-bit ADCs and, unlike other Sigmas (SD15, DP2x,Quattro), it has no AFE.
I always shoot at ISO 100, FWIW. RD black level is manual 0.
In this post I am seeking confirmation that, for the Sigma DP2s, RawDigger is displaying the X3F raw data as written to the camera's memory card with no additional scaling done by RawDigger.