Documentation

Each restriction type has a requirement that depends on the vendor list:

Type 2 is never allowed for purposes 1, 3, 4, 5 and 6, which TCF allows only with consent. TCF allows restrictions only in service-specific TC strings. c15t always writes those, so the deprecated isServiceSpecific option has no effect on restrictions. c15t copies the restrictions when the CMP starts, so changing your array afterwards has no effect.

c15t checks restrictions when the vendor list loads and again before each TC String is encoded. Unsupported restrictions include type 3, which the spec reserves, a vendor or purpose missing from the list, and a vendor with two restriction types for one purpose. They are never dropped. Loading IAB settings, saving and generating a TC String all reject with a PublisherRestrictionError exported by @c15t/iab. On a createIAB handle these are whenReady(), save() and generateTCString(). No TC String is written and no consent is recorded. Retrying whenReady() does not fetch another vendor list. The error lasts until a new vendor list is set up: with an explicit gvl option that never happens, so saving keeps failing even if the kernel later holds a different list. When the CMP follows the kernel's list instead, a replacement list is checked again and saving works once it accepts the restrictions. When a replacement vendor list makes a restriction unsupported, c15t also clears the TC authority confirmed under the previous list, so gated scripts stop until the configuration is fixed. Whenever c15t withdraws the authority it confirmed, it also removes the TC String from the euconsent-v2 cookie and localStorage entry. Because the check reads the current vendor list, a vendor that stops declaring a purpose or its flexibility makes a restriction invalid. Narrow a vendors allowlist and your restrictions together.

Saved TC Strings carry the restrictions in their PubRestrictions section, and __tcfapi('getTCData') reports them as publisher.restrictions, keyed by purpose ID, then vendor ID. A stored TC String whose restrictions differ from the current configuration is not restored. If the visitor's stored choice is otherwise current, the banner opens again, as it does after a policy change, and closes once the visitor saves. IAB gates that depend on the TC String stay denied until then. c15t also removes the superseded TC String from the euconsent-v2 cookie and localStorage entry, so vendors reading standard storage do not pick it up. An unchanged configuration restores the stored TC String without asking. When reading a string written under TCF policy version 2 or 3, c15t accepts type 2 for purposes 3 to 6, which those versions allowed. Strings c15t writes always follow the current policy.

The React, Vue, Svelte and @c15t/browser/iab preference centres list each vendor under the legal basis the restrictions leave it. A vendor whose purpose now requires legitimate interest gets an objection control instead of a consent toggle, and a prohibited purpose no longer lists the vendor. A purpose whose vendors all use legitimate interest has no consent switch, because turning one off would change nothing the vendors rely on; its objection control is the opt-out. Such a purpose does not decide its c15t category: the category follows the purposes in it that the visitor can consent to. Legitimate interest never grants a category on its own. If none of a category's purposes has a consent basis, nothing can consent to them, Accept All included, so the category stays denied. See categories under an IAB policy. Stack switches cover only the purposes some vendor processes on consent. Display-model rows expose this as hasConsentBasis. Custom preference UIs can call applyPublisherRestrictionsToGVL from @c15t/iab/headless, or pass publisherRestrictions to processGVLForDialog, to get the same vendor declarations. The configured restrictions are on the kernel's IAB state as publisherRestrictions.

Consent-gated scripts, network rules and iframes with a vendorId also apply the confirmed restrictions for that vendor:

• Type 0 blocks a target that declares the purpose in iabPurposes or iabLegIntPurposes.
• Type 1 makes a purpose declared in iabLegIntPurposes require purpose and vendor consent. Legitimate interest no longer satisfies it.
• Type 2 makes a purpose declared in iabPurposes require purpose and vendor legitimate interest. Consent no longer satisfies it.

Types 1 and 2 block the target when the vendor list does not mark the purpose as flexible for that vendor. Targets without a vendorId ignore restrictions. A target that uses only legitimate interest once restrictions apply is not blocked by a refused category, since it needs no consent; its legitimate interest signals and the visitor's objection decide. GPC and strict scope still block it, and the category stays refused for scripts that depend on it. Accept All grants the vendor signal a restriction moves a purpose to, including legitimate interest for a vendor that declares none. Legitimate interest a restriction introduces applies until the visitor objects: the preference centres show it as allowed, and saving without touching it encodes it as allowed. introducedLegitimateInterest from @c15t/iab/headless lists those purposes and vendors for custom preference UIs.