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When i did a GetCategoryFeatures call for some categories it Indicates that GTC is not avaliable for FixedPriceItems in UK, DE, FR, etc. Why?
This is due to the fact that in some countries (UK, DE, FR included) the 30 day and or GTC durations are only enabled for sellers who have a stores, that too only in some categories.(Please note that this is not available for StoreFixedPriceItems either, even thoough the GCF response says so)
Typically Users rely on the list of standard durations returned in FeatureDefinitions.ListingDurations to get the standard list of durations, but in these other(exceptional) cases they need to check to see if Category.StoreOwnerExtendedListingDurationsEnabled has a value of true for a given category, if so then the user should take the durations in StoreOwnerExtendedListingDurations.Duration and add them to the list of standard durations returned in FeatureDefinitions.ListingDurations.
You can find the elements for the store owner durations from GetCategoryFeatures api call:
Category.StoreOwnerExtendedListingDurations.Duration : Specifies the length of time an auction can be open, in days. The allowed durations vary according to the type of listing. The value GTC means Good Til Canceled.
Applicable values: See ListingDurationCodeType Category.StoreOwnerExtendedListingDurationsEnabled boolean Conditionally Defines if extended store owner listing durations are enabled in a given category. When the value of this element is true, it means the listing duration values defined in StoreOwnerExtendedListingDurations are applicable to fixed price listings in a given category. Applies to Fixed Price Listings.