The term ``patent license,'' as used in GPLv3~\S11\P4--6, is not meant to be

confined to agreements formally identified or classified as patent licenses.

GPLv3~\S11\P3  makes this clear by defining ``patent

license,'' for purposes of the subsequent three paragraphs, as ``any express

agreement or commitment, however denominated, not to enforce a patent

(such as an express permission to practice a patent or covenant not to

sue for patent infringement)''.

``Express'', as used GPLv3~\S11\P3, is a term often used in legal writing as

an antonym to ``implied''.  Thus, GPLv3's definition of ``patent license''

does not include those patent licenses which arise by

Instead, GPLv3~\S11\P3--5 are specifically concerned with explicit promises

that are purportedly legally enforceable.

Nevertheless, unlike traditional commercial patent licensing

agreements\footnote{Typically, well-drafted commercial patent license

  agreements explicitly exclude any possibility of

  implied licenses.  Thus, GPLv3's final paragraph may be unique among both commercial

  agreements and/or other Free Software licenses (both copyleft and

  non-copyleft).  Careful study of the patent licensing implications of GPL

  should not ignore this observation.  In particular, contrast carefully the

  goals of commercial patent licensing agreements and the policy goals of a

  copyleft license.  Namely, patent license granters typically draft patent license