オーデル・ナイセ線
In 1990, as part of the reunification of Germany, West Germany accepted clauses in the Treaty on the Final Settlement With Respect to Germany whereby Germany renounced all claims to territory east of the Oder–Neisse line. Germany's recognition of the Oder–Neisse line as the border was formalised by the re-united Germany in the German–Polish Border Treaty on 14 November 1990; and by the repeal of Article 23 of the Basic Law for the Federal Republic of Germany under which German states outside the Federal Republic could formerly have declared their accession.