Chapter Approved is a "stamp of approval" that Games Workshop used to put on rules published in White Dwarf that were meant to be official. Back in Third Edition, every issue of WD had a column where Andy Chambers (and other Warhammer 40,000 writers) would write rules clarifications, errata, new army lists, and experimental rules (some of which were used in later editions); these columns were then combined into annual Codex-type volumes in 2002, 2003, and 2004. These articles were on average fucking awesome and generally upped the greatness of the Dwarf immensely. Examples of awesomeness include trial rules for using Space Marine Chapters of the Cursed Founding; information on the Imperial Guard regiments of Armageddon; and rules to allow the use of Inquisitorial henchmen. It showed as well that at the time Games Workshop actually acted like a game company and gave the public something they wanted; a bit of extra fluff and some different rules to add a bit of spice to their gaming.
Unfortunately, with Chambers' departure from GW (and Games Workshop's general descent into corporate evil), the column fell by the wayside, and the "Chapter Approved" stamp is only seldom seen nowadays. At the time this also marked the removal of story and fluff elements slowly from the Dwarf in favor of more painting guides and adverts, until now any fluff is a mere whisper in the wind crowded under the latest Space Marines that you just have to buy!
Nevermind all that, Chapter Approved is back! This time as a yearly publication the first issue of which is scheduled for Christmas of 2017.
Chapter Approved 2017
Apart from updating points costs for various units and wargear (e.g. it's how they'll be updating armies whose Codexes are already out from now on, akin to the General's Handbook in Age of Sigmar), CA 2017 introduced the following.
- Rules for Apocalypse in 8th edition.
- Guidelines for Planetstrike and Stronghold Assault campaigns.
- More mission types for all three modes of play.
- Rules for designing your own custom Land Raiders for Open Play, a feature last seen in 5th edition. Only Land Raiders are demonstrated, but it's been commented that similar techniques could be used for other vehicles.
- Expanded rules for all factions that haven't gotten their Codexes yet. Everyone now has at least one unique Stratagem, WT, and Relic.
Chapter Approved 2018
Will contain the following, along with general balance changes and points cost modifications:
- The beta version of the Sisters of Battle Codex, as a combined sneak preview and chance to playtest it so the kinks can be worked out.
- Rules for designing new special characters for use in Open Play.
- Battle Honors, a Narrative Play option allowing units to level up and gain skills like in Kill-Team.
- Rules for the Looted Tank in Open Play, for the Orks.