CM93 is already a "SENC format", optimized for processing, while standard S-57 (or S-63) needs to be preprocessed to get something to render in a reasonable matter.
oeSENC - as the name says - is preprocessed as well.
The Transas TX-97 and the Navionics
sets are other examples for SENCs.
By definition all the SENCs are incompatible between each other.
One might call S-57 an exchange format, not a render format.