# வார்ப்புரு:Citation Style documentation/registration

<span id="csdoc_access_level"></span>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 the access restrictions of the external links included in a citation. : access icons do not display correctly for editors who use Modern skin.  
Four access levels can be used:
- <code>free</code>: the source is free to read for anyone (this applies in particular to articles in open access)
- <code>registration</code>: a free registration is required to access the source
- <code>limited</code>: there are other constraints (such as a cap on daily views) to freely access this source
- <code>subscription</code>: the source is only accessible via a paid subscription ("paywall")  
As there are often multiple external links with different access levels in the same citation, these values are attributed to a particular external link.  
##### Access indicators for url-holding parameters
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 <code>free</code>.
**url-holding and access-indicator parameters**  
| url | access | allowed keywords |
| --- | --- | --- |
| <code>registration</code>
<code>limited</code>
<code>subscription</code> |  |  |
| } |  |  |
not currently defined; use its alias  
##### Access indicators 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. Because the sources linked by these named-identifier parameters are not presumed to be free-to-read, they may not be marked as <code>limited</code>, <code>registration</code>, or <code>subscription</code>.  
**named-identifier and access-indicator parameters**  
| identifier | access | allowed keywords |
| --- | --- | --- |
| <code>free</code> |  |  |
| } |  |  |  
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:
-
-
-
-
-
-  
##### Ambiguous access parameters
The parameters and can also be used to indicate the access level of a citation. However, they do not indicate which link they apply to, so editors are encouraged to use and instead, when the restriction applies to . If the restriction applies to an identifier, these parameters should be omitted.  
These parameters add a link note to the end of the citation:
- ***': (deprecated) 
For online sources that require registration, set (or <code>y</code>, or <code>true</code>); yields to ***' if both are set.
 Use the appropriate access-indicator parameter
- ***': (deprecated) 
For online sources that require a subscription, set (or <code>y</code>, or <code>true</code>); supersedes ***' if both are set.
 Use the appropriate access-indicator parameter
Setting or to any value other than <code>y</code>, <code>yes</code>, or <code>true</code> will generate an error message.