Heavily favored by the Perl community, the Artistic license requires that modified versions of the software do not prevent users from running the standard version.
Artistic License 2.0Copyright (c) <year> <fullname>Everyone is permitted to copy and distribute verbatim copies of this licensedocument, but changing it is not allowed.PreambleThis license establishes the terms under which a given free software Package maybe copied, modified, distributed, and/or redistributed. The intent is that theCopyright Holder maintains some artistic control over the development of thatPackage while still keeping the Package available as open source and freesoftware.You are always permitted to make arrangements wholly outside of this licensedirectly with the Copyright Holder of a given Package. If the terms of thislicense do not permit the full use that you propose to make of the Package, youshould contact the Copyright Holder and seek a different licensing arrangement.Definitions"Copyright Holder" means the individual(s) or organization(s) named in thecopyright notice for the entire Package."Contributor" means any party that has contributed code or other material to thePackage, in accordance with the Copyright Holder's procedures."You" and "your" means any person who would like to copy, distribute, or modifythe Package."Package" means the collection of files distributed by the Copyright Holder, andderivatives of that collection and/or of those files. A given Package mayconsist of either the Standard Version, or a Modified Version."Distribute" means providing a copy of the Package or making it accessible toanyone else, or in the case of a company or organization, to others outside ofyour company or organization."Distributor Fee" means any fee that you charge for Distributing this Package orproviding support for this Package to another party. It does not mean licensingfees."Standard Version" refers to the Package if it has not been modified, or hasbeen modified only in ways explicitly requested by the Copyright Holder."Modified Version" means the Package, if it has been changed, and such changeswere not explicitly requested by the Copyright Holder."Original License" means this Artistic License as Distributed with the StandardVersion of the Package, in its current version or as it may be modified by ThePerl Foundation in the future."Source" form means the source code, documentation source, and configurationfiles for the Package."Compiled" form means the compiled bytecode, object code, binary, or any otherform resulting from mechanical transformation or translation of the Source form.Permission for Use and Modification Without Distribution(1) You are permitted to use the Standard Version and create and use ModifiedVersions for any purpose without restriction, provided that you do notDistribute the Modified Version.Permissions for Redistribution of the Standard Version(2) You may Distribute verbatim copies of the Source form of the StandardVersion of this Package in any medium without restriction, either gratis or fora Distributor Fee, provided that you duplicate all of the original copyrightnotices and associated disclaimers. At your discretion, such verbatim copies mayor may not include a Compiled form of the Package.(3) You may apply any bug fixes, portability changes, and other modificationsmade available from the Copyright Holder. The resulting Package will still beconsidered the Standard Version, and as such will be subject to the OriginalLicense.Distribution of Modified Versions of the Package as Source(4) You may Distribute your Modified Version as Source (either gratis or for aDistributor Fee, and with or without a Compiled form of the Modified Version)provided that you clearly document how it differs from the Standard Version,including, but not limited to, documenting any non-standard features,executables, or modules, and provided that you do at least ONE of the following:(a) make the Modified Version available to the Copyright Holder of the StandardVersion, under the Original License, so that the Copyright Holder may includeyour modifications in the Standard Version.(b) ensure that installation of your Modified Version does not prevent the userinstalling or running the Standard Version. In addition, the Modified Versionmust bear a name that is different from the name of the Standard Version.(c) allow anyone who receives a copy of the Modified Version to make the Sourceform of the Modified Version available to others under(i) the Original License or(ii) a license that permits the licensee to freely copy, modify and redistributethe Modified Version using the same licensing terms that apply to the copy thatthe licensee received, and requires that the Source form of the ModifiedVersion, and of any works derived from it, be made freely available in thatlicense fees are prohibited but Distributor Fees are allowed.Distribution of Compiled Forms of the Standard Version or Modified Versionswithout the Source(5) You may Distribute Compiled forms of the Standard Version without theSource, provided that you include complete instructions on how to get the Sourceof the Standard Version. Such instructions must be valid at the time of yourdistribution. If these instructions, at any time while you are carrying out suchdistribution, become invalid, you must provide new instructions on demand orcease further distribution. If you provide valid instructions or ceasedistribution within thirty days after you become aware that the instructions areinvalid, then you do not forfeit any of your rights under this license.(6) You may Distribute a Modified Version in Compiled form without the Source,provided that you comply with Section 4 with respect to the Source of theModified Version.Aggregating or Linking the Package(7) You may aggregate the Package (either the Standard Version or ModifiedVersion) with other packages and Distribute the resulting aggregation providedthat you do not charge a licensing fee for the Package. Distributor Fees arepermitted, and licensing fees for other components in the aggregation arepermitted. The terms of this license apply to the use and Distribution of theStandard or Modified Versions as included in the aggregation.(8) You are permitted to link Modified and Standard Versions with other works,to embed the Package in a larger work of your own, or to build stand-alonebinary or bytecode versions of applications that include the Package, andDistribute the result without restriction, provided the result does not expose adirect interface to the Package.Items That are Not Considered Part of a Modified Version(9) Works (including, but not limited to, modules and scripts) that merelyextend or make use of the Package, do not, by themselves, cause the Package tobe a Modified Version. In addition, such works are not considered parts of thePackage itself, and are not subject to the terms of this license.General Provisions(10) Any use, modification, and distribution of the Standard or ModifiedVersions is governed by this Artistic License. By using, modifying ordistributing the Package, you accept this license. Do not use, modify, ordistribute the Package, if you do not accept this license.(11) If your Modified Version has been derived from a Modified Version made bysomeone other than you, you are nevertheless required to ensure that yourModified Version complies with the requirements of this license.(12) This license does not grant you the right to use any trademark, servicemark, tradename, or logo of the Copyright Holder.(13) This license includes the non-exclusive, worldwide, free-of-charge patentlicense to make, have made, use, offer to sell, sell, import and otherwisetransfer the Package with respect to any patent claims licensable by theCopyright Holder that are necessarily infringed by the Package. If you institutepatent litigation (including a cross-claim or counterclaim) against any partyalleging that the Package constitutes direct or contributory patentinfringement, then this Artistic License to you shall terminate on the date thatsuch litigation is filed.(14) Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER ANDCONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIEDWARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, ORNON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW.UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FORANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAYOUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCHDAMAGE.