# Rights and licenses

This course is an aggregate with two license routes.

The 36 units inherited from the earlier course draft are modified versions of that GFDL work. Each remains under the GNU Free Documentation License, Version 1.2 only, with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. The revised wording and organization do not relicense inherited GFDL expression. New contributions to those units were dedicated to CC0 to the extent rights exist, and the combined modified units continue under GFDL 1.2 only.

The 20 added lessons are separate works dedicated to CC0. Their source files and license routes are identified in `course.json`.

External works appear as citations, mathematical antecedents or comparison readings. Their source files, scans, OCR and proof text are not included in this public course. They retain their own licenses and rights.

The modified-version notice is in [Title page](TITLE_PAGE.md), and the version record is in [History](HISTORY.md). The complete GFDL 1.2 text is in [COPYING](COPYING). Machine-readable per-unit routes and exact source identities accompany the local course audit.

Anyone distributing one of the 36 GFDL units separately should keep its title and history information, its license notice, and a copy of `COPYING` with it.


## Separate editorial supplement

The original explanatory proofs in Exact comparisons for the original Dereziński TeX are a separate CC0 contribution. This supplement adds no inherited lesson and changes none of the 36 GFDL or 20 CC0 lesson designations. The linked original-author TeX is not redistributed in this edition.


## Mixed-order inverse supplement

The complete explanatory proofs in Mixed inverses with two independent orders and phase-space multipliers, and its original reproducible figure, are separately dedicated under CC0 1.0. They add no inherited lesson and change none of the 36 GFDL or 20 CC0 lesson designations. Mathematical formulas from the identified course example remain visible with their source link; no external original-author text is redistributed.


## Sobolev and boundary receiver supplement

The explanatory proofs in Sobolev and boundary maps of the full mixed inverse and its reproducible figure are dedicated under CC0 1.0. The original matrix and course statements remain identifiable. The 36 GFDL and 20 CC0 lesson designations are unchanged; no external author text is redistributed.