title: Type conflict within DELETE itab1 FROM itab2?
body: <p>I've had a dump recently, </p>
  
  <pre><code>DATA: gt_data    TYPE SORTED TABLE OF ty_data WITH NON-UNIQUE KEY bukrs gaapnm,
       ...
       lt_tabdel  TYPE standard TABLE OF ty_data.
  
    LOOP AT gt_data ASSIGNING &lt;gf_data&gt;.
      IF &lt;gf_data&gt;-KANSW + &lt;gf_data&gt;-KAUFW = 0.
        APPEND &lt;gf_data&gt; TO lt_tabdel.
      ENDIF.
    ENDLOOP.
  
    IF lt_tabdel IS NOT INITIAL.
      DELETE gt_data FROM lt_tabdel.
    ENDIF.
  </code></pre>
  
  <p>And on the line with deleting table from internal table - i've had a dump: In statement
  Convert object to integer
  only numerical type data objects are supported at argument position
  "object".
  In the present case, operand "object" has the non-numerical data type "TABLE
   OF TY_DATA". I just can't understand - why? Both of it had the same type... So, it will be great if you could provide some advice and a bit of explanation of error origins.</p>