Help in understanding a PCR

Hi Experts

can any one help me in understanding what following PCR is doing?

ZERO=&TWPB VVVV Set zero

TABLEWPBP  Read table fields

VARGBAPZNR Tab.field VVVVV v.ky

  **

  01

    NUM=01     Set

    ADDWT&TWPB VAR  Variable table

Regards,

Jignya