Usage of IEQ

Hi,

I came across this snippet, but can't understand what is the usage of IEQ.
The wo_kunnr-low will be populated by the kunnr found in the select, but just after that there is my workarea wo_kunnr(3) = 'IEQ'.

From this I shoud get true or false based on what I find on internet, but IEQ which values is comparing in here?

TYPES: BEGIN OF ty_opt,
           sign(1)   TYPE c,
           option(2) TYPE c,
           low(50)   TYPE c,
           high(50)  TYPE c,
         END OF ty_opt.

 DATA: s_kunnr    TYPE STANDARD TABLE OF ty_opt,
        s_pan     TYPE STANDARD TABLE OF ty_opt,
        s_card    TYPE STANDARD TABLE OF ty_opt,
        gt_cards  TYPE STANDARD TABLE OF zecc_cards_kunnr,
        wo_kunnr like line of s_kunnr.


clear wo_kunnr.
    SELECT  kunnr INTO wo_kunnr-low FROM ztable_kunnr WHERE
      pan IN s_pan.
      wo_kunnr(3) = 'IEQ'.
      APPEND wo_kunnr to s_kunnr.
    ENDSELECT.
    SORT s_kunnr.