Many thanks, Technical & DippyWe'll contact Microchip for clarification.
I am in the process of updating the PIC18F1xK22 and PIC18F2x/4xK22 datasheets. This is one of the issues being fixed in those datasheets. All of the PORTC pin have Schmitt Trigger input buffers. The table 1-2 has them incorrectly listed as TTL. This is fixed in the update of the datasheet, but I am not sure when it will be released as I am still making edits.