(Note: some of this material is taken directly from the Halopedia Wikia, and edited for our use.)
Canon is defined as characters, locations, and details that are considered to be genuine (or "official"), and those events, characters, settings, etc. that are considered to have inarguable existence within the fictional universe.
Halo Canon sources applicable to costumes:
|Halo: Combat Evolved||Halo 2||Halo 3||Halo 3: ODST||Halo Wars||Halo: Chronicles||Halo: Reach|
|Halo: The Fall of Reach||Halo: The Flood||Halo: First Strike||Halo: Ghosts of Onyx||Halo: Contact Harvest||Halo: The Cole Protocol||Halo Graphic Novel|
|Halo: Uprising||Halo Wars: Genesis||The Art of Halo||Halo: Prima's Official Strategy Guide||Halo 2: The Official Game Guide||Halo 3: The Official Strategy Guide|
|Halo 3 Announcement Trailer||Halo 3 Trailer - Behind the Scenes||Halo Wars Announcement Trailer||ViDocs|
Notes regarding SourcesEdit
Please note that there are "levels" of Canon, where the information in one source will overwrite the infomation gained from another. In costuming, an image from a canon source overwrites a written description, but only if there is a significant conflict. Otherwise it can be assumed that the image reflects an attempt to meet the quality text desciption.
For example, if a character is described as having hands wrapped in black electrical tape, but is shown graphically to have black gloves on, there is a conflict which could "go either way". However, if the graphic screenshot image shows bare hands, the bare hands are "more" canon than the written description.
The reason for this is twofold; Most people will find the graphical representation to be the most familiar version, and the "intended media" for the Halo universe is the video games themselves.
However, it should be noted that printed screeenshot images in a canon book overwrite any that are viewed through the Television or Computer. This is due to the fact that there are inconsistencies which arise, based on aspect ratios, and color abilities of the equipment being used to view the material. This clarification is most important when trying to establish canonical colors.
Toys are slightly more canon than a written description, but never more than a printed image or screenshot. Changes are often made to permit a fictional image to be made out of the materials at hand, at the scale required. For example, a paperthin mask is not something you can dutifully replicate on a toy because the scale would cause it to be prohibitively thin, and as such, toys are often suspect.
Trailers should be used with caution as they may not be accurate to the appearance of the finished game.
However, please note that this is intended to be a guide, rather than an absolute decree of some sort and you are of course permitted to do whatever you want. If anyone ever asks you if you have (or are working on) a canon suit, you'll have a better idea of what to say. It's also possible that folks will want to completely copy a source, such as the toy in the hopes of replicating a canon toy version.