LOOP, first thing is IF

[larshp]

LOOP AT it_asdf ASSIGNING FIELD-SYMBOL(<ls_asdf>).

  IF <ls_asdf>-obj_up IS NOT INITIAL.

... ENDIF.

• nothing here ENDLOOP.

[larshp]

another example,

        loop at lt_table into ls_foo.
          if ls_foo-start le sy-datum.
            append ls_foo to lt_result.
          endif.
        endloop.

[larshp]

another example,

        LOOP AT lt_filter_select_options INTO DATA(ls_filter_select_options).
          IF ls_filter_select_options-property EQ 'MATNR'.
...
          ENDIF.
        ENDLOOP.