The is a question related to T=1 protocol for smartcard. The scenario is as follows: The interface device has to send, say 5 chained I-blocks to the card. So the M-bit is set for the first four blocks and cleared for the last one.
Can the card, say during the transfer of 2nd I-Block send an IFS or WTX request as response? OR the card MUST reply with R-blocks always for chained I-Blocks.
Regards, Jain.
ISO 7816-3, section 11.6.2.2 Chaining, appears clear to me in that respect:
You have to sent (ISO-speak shall) a R-block with either positive or negative acknowledge.
It's neither a sensible time for an IFS (field size negotiation must have happend before, otherwise the terminal would not know, at which position to chain), nor a WTX (card processing only starts after the complete APDU has been received).