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A Swarm client or proxy can include this header with the PUT, COPY, APPEND, GET, and HEAD methods to make it conditional. This feature allows efficient cached information updates with a minimum amount of transaction overhead. The header value is either a single quoted string (possibly with some ignored flags outside the quotation marks), a comma-separated list of quoted strings, or a single asterisk, anything after which is be ignored.
Examples of If-None-Match request headers:
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