Sylladex

The Sylladex is the inventory system in Homestuck and HomeWard. Most of the characters have a Sylladex to store and retrieve things from, which consists of two decks of cards: the Captchalogue Deck and the Strife Deck.

As shown with Olli, using the Deck is not obligatory, and is simply a common way of carrying a lot of different items at once with ease. These cards have codes on their backs that can be entered on the Punch Designix to create a punched card.

The word "sylladex" is presumably a portmanteau of "syllabus" and "index"; its plural is "Sylladices".

Captchalogue Deck
The word "captchalogue" is a portmanteau of the words "captcha" and "catalogue". The word "captcha" hints the codes on the back of each card.

The Captchalogue Deck is where objects are stored to be used later.

Objects of any size and shape are stored on Captchalogue Cards, and while stored, they have no physical size or weight. It has been found that basic Captchalogue Cards cannot hold items over certain masses. To Captchalogue, say, The Earth, one would need a Deck with a Space modifier.

However, there is a limit to how many different items can be captchalogued, based on the number of cards in the character's deck. Captchalogue cards can be added to the Captchalogue Deck by captchaloguing them and then forcing them out of the deck.

Also, living things can apparently be captchalogued. It is unknown what it feels like to be inside a captchalogue card. It is also unknown if a person can captchalogue themselves, though this would probably be unlikely, since doing so would create a paradox due to the Captchalougue card being held by the player, who is stored in the card.

Punched Captchalogue Card
Punched cards are captchalogue cards that have been punched using the Punch Designix. The items stored in these cards can't be retrieved, but they can be duplicated using the other items from the Phernalia registry. To use a punched card, one must place it in the Totem Lathe to carve a Cruxite dowel into a totem unique to that card. That totem can then be used in the Alchemiter to re-create the object on the card, as long as one has the required grist.

Cards have 8 characters, with each character being assigned an 8-bit binary number.

Fetch Modi
The manner in which items are stored and retrieved from the Sylladex is based on the Fetch Modus that is currently active.

(i'm gonna detail the mechanics later im hella tired)

Each Fetch Modus has a unique color given to all Captchalogue cards in a Sylladex that uses it. When outside of a Sylladex, Captchalogue cards are red. Each Fetch Modus is unique. Due to their programmability, anyone can create or modify a Modus if they understand it. Consequently, Fetch Modi can be based on anything and everything, such as board games, data structures, actions, etc.

9x4 Inventory
Blues' Fetch Modus.

Bottle
Sammy's Fetch Modus.

Tesseract
Olli's first Fetch Modus.

Bookshelf
Olli's second Fetch Modus.

Constellation
Rana's Fetch Modus

Scrap
Red's Fetch Modus.