-- real code starts here
form_name varchar2(30) := name_in('system.current_form'); 
block_name varchar2(30) := name_in('system.cursor_block');
item_name varchar2(30) := name_in('system.current_item');
-- constants for some glob var values
LC_TRUE constant varchar2(1) := 'Y';
LC_FALSE constant varchar2(1) := 'N';
LC_PROGRESS constant varchar2(10) := 'INPROGRESS';
LC_INITIAL constant varchar2(7) := 'INITIAL';
-- counter to keep track of custom.pll instance
l_event_cnt number := 0;
-- marker if customer has changed
l_cust_changed boolean := false;
-- customer number
l_cust_nbr number;
-- new att6 value
l_new_att6 varchar2(30) := null;
BEGIN
  /**
   * JUST FOR DEBUGGING!
   * counts the events caught by custom.pll, to identify the
   * instance which is poping up a window
   */
  IF (event_name='WHEN-NEW-FORM-INSTANCE') THEN
    copy('0','GLOBAL.XX_'||form_name||'_EVENT_CNT');
  ELSE
    l_event_cnt := to_number(name_in('GLOBAL.XX_'||form_name||'_EVENT_CNT'));
    copy(to_number(name_in('GLOBAL.XX_'||form_name||'_EVENT_CNT'))+1,'GLOBAL.XX_'||form_name||'_EVENT_CNT');
  END IF;
  /**
   * JUST FOR DEBUGGING!
   * Observer at start for att6 at order
   */
  IF (form_name IN ('OEXOEORD')) THEN
    IF (event_name='WHEN-NEW-FORM-INSTANCE') THEN
      copy(LC_INITIAL,'GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD');
    END IF;
    IF (event_name = 'WHEN-NEW-ITEM-INSTANCE' 
        AND name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD') = LC_INITIAL 
        AND name_in('ORDER.SOLD_TO_ORG_ID') IS NOT NULL
    ) THEN
      copy(name_in('ORDER.ATTRIBUTE6'),'GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD');
    END IF;
    IF (nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD'),'<NUL>') != LC_INITIAL
        AND nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD'),'<NUL>') != nvl(name_in('ORDER.ATTRIBUTE6'),'<NUL>')
    ) THEN
      fnd_message.set_string(l_event_cnt||'/ '||block_name||'.'||item_name||' '||event_name||': start, changed att6 from '||replace(nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD'),'<NUL>'),chr(0),'chr0')||' to '||replace(nvl(name_in('ORDER.ATTRIBUTE6'),'<NUL>'),chr(0),'chr0'));
      fnd_message.show;
      copy(name_in('ORDER.ATTRIBUTE6'),'GLOBAL.XX_'||form_name||'_ATT6_OBS1_OLD');
    END IF;
  END IF;
  /**
   * REAL CODE
   * Observer for customer number
   */
  IF (form_name IN ('OEXOEORD')) THEN
    IF (event_name='WHEN-NEW-FORM-INSTANCE') THEN
      copy(LC_INITIAL,'GLOBAL.XX_'||form_name||'_CUST_OLD');
    END IF;
    IF (event_name = 'WHEN-NEW-ITEM-INSTANCE' 
        AND name_in('GLOBAL.XX_'||form_name||'_CUST_OLD') = LC_INITIAL 
        AND name_in('ORDER.SOLD_TO_ORG_ID') IS NOT NULL
    ) THEN
      copy(name_in('ORDER.CUSTOMER_NUMBER'),'GLOBAL.XX_'||form_name||'_CUST_OLD');
    END IF;
    IF (nvl(name_in('GLOBAL.XX_'||form_name||'_CUST_OLD'),'<NUL>') != LC_INITIAL
        AND nvl(name_in('GLOBAL.XX_'||form_name||'_CUST_OLD'),'<NUL>') != nvl(name_in('ORDER.CUSTOMER_NUMBER'),'<NUL>')
    ) THEN
      l_cust_changed := true;
      copy(name_in('ORDER.CUSTOMER_NUMBER'),'GLOBAL.XX_'||form_name||'_CUST_OLD'); -- this will prevent from running code below in paralell instance of custom.pll
    END IF;
  END IF;

  /**
   * REAL CODE
   * change dependend data of DFF by customer
   */
  IF (l_cust_changed) THEN
    fnd_message.set_string(l_event_cnt||'/ '||block_name||'.'||item_name||' '||event_name||' starting change of att6');
    fnd_message.show;
    l_cust_nbr := name_in('ORDER.CUSTOMER_NUMBER');
    -- clear old att6 field
    copy(NULL,'ORDER.ATTRIBUTE6');
    -- get data and if there is one write it to att6
    BEGIN
      SELECT myfield INTO l_new_att6 FROM sometable WHERE custnbr = l_cust_nbr AND ROWNUM = 1;
      copy(l_new_att6,'ORDER.ATTRIBUTE6');
    EXCEPTION WHEN no_data_found THEN
      null;
    END;
    -- commit the form -> will trigger when-validate-record on paralell instance
    do_key('commit_form');
    fnd_message.set_string(l_event_cnt||'/ '||block_name||'.'||item_name||' '||event_name||' end of change of att6');
    fnd_message.show;
  END IF;

  /**
   * JUST FOR DEBUGGING!
   * Observer at end for att6 at order
   */
  IF (form_name IN ('OEXOEORD')) THEN
    IF (event_name='WHEN-NEW-FORM-INSTANCE') THEN
      copy(LC_INITIAL,'GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD');
    END IF;
    IF (event_name = 'WHEN-NEW-ITEM-INSTANCE' 
        AND name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD') = LC_INITIAL 
        AND name_in('ORDER.SOLD_TO_ORG_ID') IS NOT NULL
    ) THEN
      copy(name_in('ORDER.ATTRIBUTE6'),'GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD');
    END IF;
    IF (nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD'),'<NUL>') != LC_INITIAL
        AND nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD'),'<NUL>') != nvl(name_in('ORDER.ATTRIBUTE6'),'<NUL>')
    ) THEN
      fnd_message.set_string(l_event_cnt||'/ '||block_name||'.'||item_name||' '||event_name||': end, changed att6 from '||replace(nvl(name_in('GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD'),'<NUL>'),chr(0),'chr0')||' to '||replace(nvl(name_in('ORDER.ATTRIBUTE6'),'<NUL>'),chr(0),'chr0'));
      fnd_message.show;
      copy(name_in('ORDER.ATTRIBUTE6'),'GLOBAL.XX_'||form_name||'_ATT6_OBS2_OLD');
    END IF;
  END IF;