Where in the search report any document is cited for reasons (in particular as evidence – see B‑VI, 5.6) other than those referred to in the foregoing paragraphs, for example:[Art. 117(1)(c); ]
such document is indicated by the letter "L". Brief reasons for citing the document are given. In the specific case where the search division considers no documentary evidence to be necessary for the claimed subject-matter, as it is deemed to be notorious (see B‑VIII, 2.2), the reasoning behind not citing any prior-art documents is given in the search opinion.
The citation of "L" documents need not be linked to any of the claims. However, where the evidence which they provide relates only to certain claims (for example the "L" document cited in the search report may invalidate the priority claim in respect of certain claims only), then the citation of the document is linked to those claims, in the manner indicated in B‑X, 9.3.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/b_x_9_2_8.htm
Date retrieved: 17 May 2021