NI Act help

This Sec 98 point no.1 can be easily understood by applying the logic of facultative  endorsement.

Facultative endorsement means where endorser revokes some rights or increases his liabilty under an instrument. E.g. " Pay to Sneha or order--- notice of dishonour waived".

In above case of endorsement we see notice of dishonour is not necessary.

As far as point 2 is concerned its self explanatory. See in that line, when the party revokes(countermand) the paying of amount by another party. So in that it becomes obvious not to furnish any notice when the liabilty itself is abandoned.