adfilt/Wiki/SyntaxMeaningsThatAreActuallyHumanReadable.md

All up-to-date significant adblockers¹

Element removal

• ##. / ## / ###: Hides parts of a page.
• #@#: Whitelists parts of a page to make them load.
• [href="text"]: Finds page elements whose values in the F12 filetree console contains such a value. The value can be href, id, class, type, or several other things.
• [href^="text"]: Same as above, except it finds anything whose value begins with the text.
• [href$="text"]: Same as above, except it finds anything whose value ends with the text.
• [href*="text"]: Same as above, except it finds anything whose value contains the text anywhere within it.
• :not(.element): Finds page elements that doesn't contain a specified element or text string. Can be paired with other syntaxes á la :not(:-abp-contains(Example text)).
• :-abp-contains(text): Finds page elements that contains such text within it.
• :-abp-has(.element): Finds page elements that contains such an element within it.
• :nth-of-type(n) / :last-of-type / :only-of-type: Finds page elements that are at a specific numerical position in a set.
• :before / :after: Removes the pseudo-elements that belong to a page element.
• a / div / iframe / img (among others): Looks for page elements that are specific element types, as seen in the F12 filetree console.

File blocking

• ||: Blocks resources from domains or parts thereof from being loaded. For non-domain-specific resources, no pre-emption is needed at all.
• @@: Whitelists resources from specific URLs to make them load.
• $third-party / $3p: Ensures that resources from a domain are only blocked if you're not visiting the domain itself.
• $domain=: Ensures that resources from a domain are only blocked if you're visiting a specified website.
• $generichide: Prevents all non-domain-specific hiding entries from working on a website.
• $script: Blocks resources from domains or parts thereof from being loaded, but only if it's a script, e.g. a JavaScript runtime.
• $document: Shows a danger warning when loading a page.
• $csp: Inserts additional Content Security Policies into the page.

Universal

• ! / # : Marks the start of a comment that shall not be interpreted as an entry.
• ~: Means that an entry does not apply to a specific domain.
• /\/\/\/ and similar: Text detections in RegEx format.
• [Adblock Plus n.n]: Used by Adblock Plus, AdBlock, and forks of them to determine if they should load the filterlist. Number is the intended minimum ABP version. 2.0 and 1.1 are most common; 3.1 and higher is on the rise and can be used to block support for old or low-quality forks. This has no effect on uBO or its forks.

Nano Adblocker, uBlock Origin and AdGuard only:

• :style: Changes the CSS values of an element, in much the same way as what userstyle extensions like Stylish would've done.
• { }: Same as above.
• $badfilter: Deactivates a resource-blocking entry, even if it is present in another list.
• :has-text: Same as :-abp-contains.
• :has: Same as :-abp-has.
• !#if: Specifies that a section of entries only applies to specific platforms or extensions. Closed out by !#endif.

Nano Adblocker and uBlock Origin only:

• !#include: Embeds another filterlist that is hosted on the same domain (with numerous restrictions).
• ##+js (prev. ##script:inject): Invokes a script that is embedded in those extensions, and usually using the script to modify a value on the site.
• :xpath: An entry written with the very advanced Xpath syntax.
• $important: Makes a resource-blocking entry take precedence over another whitelisting entry.
• 127.0.0.1 / 0.0.0.0 / ::1: Used by "hosts" system files to signify that network requests to such a domain shall be redirected to a local-only IP address, thus preventing it from loading. Nano and uBO treats it the same as ||.
• ##^: Blocks resources before they've even been loaded, based on their values in View source instead of their F12 ones.
• $redirect: Redirects resources to a neutered version that has been embedded in those extensions.
• :matches-css: Looks for page elements whose existing native (i.e. non-inherited) CSS values match those of the criteria.
• :matches-css-before: Same as above, but looks for CSS values in its pseudo-elements instead.
• $first-party / $1p: Ensures that resources from a domain is only blocked if you're visiting the domain itself.

I honestly don't know what these ones do:

• :-abp-properties
• $xmlhttprequest

Particularly important usage notes

• ##. / ## / ### entries can either be generic, in which they have no domains in front of them; or domain-specific, where they have one or more domains in front of them, separated by commas. Only Nano and uBO support wildcard asterisks (*) in such domains, while other adblockers do not.
• || entries do support asterisk wildcards, but only in the criteria text. Additionally, when using $domain=, domains are separated with vertical lines, since commas are instead used to stack multiple $ values.
• $generichide entries must start with @@||.
• ABP is known to severely struggle with handling :style entries, to the point where having ABP try to load a list with such an entry will cause it to invalidate the list and all its entries.
• To make the text detection for :-abp-contains and :has-text case-insensitive, wrap the paranthesised text into (/Example text/i).
• 127.0.0.1 / 0.0.0.0 / ::1 supports only whole domains, and it can not be narrowed down to subdomains or elements.
• The " in [href="text"] is optional, but only if the criteria text is only a single word.
• In :-abp-has and :has, it is not needed to pre-empt the criteria elements with ##.
• :style and { } does not allow to change background-image into a URL value.
• It is claimed in this comment that Safari does not properly accept the use of $third-party.

¹ = Includes Nano Adblocker, uBlock Origin ≥1.14.0, AdGuard, Adblock Plus version ≥3.1, and AdBlock. It does not include Brave Browser, Slimjet, uBlock non-Origin, Adblock Plus for IE, Tracking Protection List, AdAway, or Blokada, whose syntax supports are considerably inferior to the above list.