One-shots can be added to the site provided they been published in a reputable, professional, Japanese magazine.
They are single, standalone works with a self-contained story. This means that any series with more than one chapter is not a one-shot.
It is acceptable for both the standalone one-shot and any anthology or collection it is compiled into to be added to the website. These must be linked through the ‘contains’ and 'compilation' relations.
The now-defunct magazine, Pure Yuri Anthology Hirari, which solely published one-shots, released an anthology containing a selection of six of their one-shots:
Adding Isshun no Asterism (one-shot) to Shuuden ni wa Kaeshimasu (anthology) with the 'contains' relation automatically adds Shuuden ni wa Kaeshimasu as the ''compilation' to Isshun no Asterism, and vice versa.
In the case of retroactively creating standalone entries when the compiled volume already exists in the database, the standalone one-shot must have the date when it was first published, not the date the anthology or collection was published (where applicable).
Anthologies should be have both start and end dates set to the day that the anthology was released, not the dates between oldest and newest one-shots contained within.