Citations of online sources that require registration or a subscription are acceptable in Wikipedia as documented in Verifiability § Access to sources. As a courtesy to readers and other editors, editors should signal restrictions on access to material provided via the external links included in a citation. These levels describe requirements or constraints related to accessing and viewing the cited material; they are not intended to indicate the ability to reuse, or the copyright status, of the material, since that status is not relevant to verifying claims in articles.   Four access levels can be used: access indicator for named identifiers:  9px|link=|alt=Freely accessible|Freely accessible free: the source is free to read for anyone (from the viewpoint of the provider of the source – could still be blocked by client-side filtering or safeguarding, or distributor-based geoblocking) access indicators for url-holding parameters:  9px|link=|alt=Free registration required|Free registration required registration: a free registration with the provider of the source is required to access the source, even if a limited preview, abstract or review may still be available without registration  9px|link=|alt=Free access subject to limited trial, subscription normally required|Free access subject to limited trial, subscription normally required limited: there are other constraints (such as a cap on daily views, a restriction to certain day or night times, or providing the contents only to certain IP ranges/locales on behalf of the provider of the source) to freely access this source as a whole  9px|link=|alt=Paid subscription required|Paid subscription required subscription: the source as a whole is only accessible via a paid subscription with the provider of the source ("paywall"), even if a limited preview, abstract or review may still be available without subscription  As there are often multiple external links with different access levels in the same citation, each value is attributed to a specific external link.  Access indicators for url-holding parameters  Online sources linked by , , , , , , and  are presumed to be free-to-read. When they are not free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation. Because the sources linked by these url-holding parameters are presumed to be free-to-read, they may not be marked as free.  + URL-holding and access-indicator parameters URL Access Allowed keywords    registration 9px|link=|alt=Free registration required|Free registration requiredlimited 9px|link=|alt=Free access subject to limited trial, subscription normally required|Free access subject to limited trial, subscription normally requiredsubscription 9px|link=|alt=Paid subscription required|Paid subscription required              For example, this cites a web page that requires registration but not subscription:  {{cite web |url=https://example.com/nifty_data.php |url-access=registration |date=2021-04-15 |title=Nifty example data}}  which renders as:  Access indicator for named identifiers  Links inserted by named identifiers are presumed to lie behind a paywall or registration barrier – exceptions listed below. When they are free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation.  When the sources linked by these named-identifier parameters are not presumed to carry a free-to-read full text (for instance because they're just abstracting services), they may not be marked as limited, registration, or subscription.  + Named-identifier and access-indicator parameters Identifier Access Allowed keywords    free 9px|link=|alt=Freely accessible|Freely accessible              Some named-identifiers are always free-to-read. For those named identifiers there are no access-indicator parameters; the access level is automatically indicated by the template. These named identifiers are:  For embargoed  that will become available in the future, see .