２重角括弧。角括弧（square brackets、 [ ]）を２重にしたもの（[]）。クレームなどの補正において、削除した単語等が５文字以下の場合などに、削除したものであることを示すために用いられる（例：[[eroor]]）。MPEP714IIB。５文字以上の単語や文章を削除したことを示す場合は、strike-through（取り消し線）を用いる（例：
37 CFR 1.121(b)(1)(ii) requires that the full text of any replacement paragraph be provided with markings to show all the changes relative to the previous version of the paragraph. The text of any added subject matter must be shown by underlining the added text. The text of any deleted subject matter must be shown by strike-through except that double brackets placed before and after the deleted characters may be used to show the deletion of five or fewer consecutive characters (e.g., [[eroor]]). The term “brackets” set forth in 37 CFR 1.121 means square brackets – [ ], and not parentheses – ( ). The text of any deleted subject matter must be shown by being placed within double brackets if strike-through cannot be easily perceived (e.g., deletion of the number “4” must be shown as []). As an alternative to using double brackets, however, extra portions of text may be included before and after text being deleted, all in strike-through, followed by including and underlining the extra text with the desired change (e.g.,
number 4 asnumber 14 as). For added paragraphs, 37 CFR 1.121(b)(1)(iii) requires that the full text of any added paragraph(s) be presented in clean form without any underlining. Similarly, under 37 CFR 1.121(b)(1)(iv), a marked up version does not have to be supplied for any deleted paragraph(s). It is sufficient to merely indicate or identify any paragraph that has been deleted. The instruction to delete may identify a paragraph by its paragraph number, page and line number, or include a few words from the beginning, and end, or the paragraph, if needed for paragraph identification.