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Note: When using the If-Modified-Since header it is recommended that you use a date retrieved from the Last-Modified header of a previous request to the same service. The reason for this is that the service expects that the parsed date retrieved from the If-Modified-Since-header is an exact match (with millisecond precision) to the date used in the Last-Modified header. The service still respect and parses all the date-formats mentioned in http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1.
OPDS format
The OPDS format is a specification based on the ATOM feed standard. Each book in the bookshelf is represented as an <entry> element with basic metadata and links to download and cover images. Below are some examples on the typical different types of entries.
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