smartcard - Select EF on a smart card via its SFI -

Some smart cards provide the option of referencing the file by SFI (short file identifier), which is a 5-bit number.

. On the contrary, a specific file identifier is 2 bytes long.

I need some help with finding out how I do this, because I failed to get an answer inside.

First, section 5.3.1.1 states (emphasis my)

Selection by Small EF Identifier - A small EF identifier to any EF Can be referred. It consists of five bits which are not identical, i.e. any number from one to thirty. When used as a small EF identifier, the number refers to zero, i.e., 00000 in binary, current EF, at the MF level, number thirty, i.e., 11110 is binary, reserved (see 8.2.1.1). Short eas identifiers can not be used as paths or EF identifiers (e.g., in a SELECT command).

My method of interpreting this sentence "can not use SFI to choose a file on a smart card" - which I do not expect.

Next, section 7.1.1 specifies how SELECT APDU commands are used; Table 39 specifies the content of P1, however, none of the examples tell how to address it through SFI (all of which are all 2-byte identifiers).

So my questions are:

1. What is the logic behind adding SFI? Was 2 bytes per identifier too high?
2. How can one file be selected, if its SFI is known?

After some additional research, I got answers to my questions.

1. A file can be read directly through SFI, without first selecting it. This allows you to save time (since no time has been spent on selection).
2. As discussed in # 1, the SFI thing is that you can read it immediately, thus the instructions which can be read in a file that its SFI is known, the details of other orders Finds - Read Binaries, Reed Records etc. See section 7.2.2 of the same doctor.