Doubts to understand C-APDU and R-APDU commands

I began to study basic notions of APDU command and response these days and i'm in a doubt about the use of the Lc and data track and his meaning. For example, if i write a command like: 00 A4 04 00 0E 31 50 41 59 2E 53 59 53 2E 44 44 46 30 31 00 I'd say that his (correct me case if i'm wrong)

CLA = is equal 00
INS = A4 that is SELECT
P1 = 04 by his first record name
P2 = 00 as default
Lc = 0E = exact length of 14 Bytes
Data = where it's my doubt
Le = 00 as default, and if it was equal another value what happens?

My doubt is about understand the clearly meaning of the Lc (exact command length), data and Le (maximum response length), how am i do to know what is this data instruction mean? and am i supposed to turn it into a text?

Solution

6F 15 84 0E 31 50 41 59 2E 53 59 53 2E 44 44 46 30 31 A5 03 88 01 01 90 00 would be parsed as

 
6F File Control Information (FCI) Template
16 Length in hex
    84 Dedicated File (DF) Name
    0E Length in hex
        315041592E5359532E4444463031    =>1PAY.SYS.DDF01
    A5 File Control Information (FCI) Proprietary Template
    03 length in hex
        88 Short File Identifier (SFI)
        01 length in hex
            01
    90 00 Successful operation

Simply, you can use this to parse your response TPDUs :-)