MediaWiki:Api-help-datatypes/en

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Input to MediaWiki should be NFC-normalized UTF-8. MediaWiki may attempt to convert other input, but this may cause some operations (such as edits with MD5 checks) to fail.

Some parameter types in API requests need further explanation:

boolean
Boolean parameters work like HTML checkboxes: if the parameter is specified, regardless of value, it is considered true. For a false value, omit the parameter entirely.
timestamp
Timestamps may be specified in several formats, see the Timestamp library input formats documented on mediawiki.org for details. ISO 8601 date and time is recommended: 2001-01-15T14:56:00Z. Additionally, the string now may be used to specify the current timestamp.
alternative multiple-value separator
Parameters that take multiple values are normally submitted with the values separated using the pipe character, e.g. param=value1|value2 or param=value1%7Cvalue2. If a value must contain the pipe character, use U+001F (Unit Separator) as the separator and prefix the value with U+001F, e.g. param=%1Fvalue1%1Fvalue2.