= How to pick a slice name =

Slice names are public, reusable and unique.
 * ''Public'' means you should expect that anyone could see the name of your slice.
 * ''Unique'' means that only one slice with that identifier[#Note *] can exist ''in each project'' at any given point in time.
 * ''Reusable'' means that once a slice has expired, that slice name may be reused to name a new slice.

In general, slice names should:
     * be at most 19 characters
     * contain only the following characters: a-z, A-Z, 0-9, - (uppercase and lowercase alphanumeric characters and dash)
     * not start with '-' (dash) 
     * Note: The '_' (underscore) character can not be used.

While enforcement of these rules is not consistent across all parts of GENI, following these rules will ensure compatibility throughout GENI.

== Note ==
Actually, it's the ''slice URN'' that must be unique.  A slice [wiki:GeniApiIdentifiers URN] is an identifier that includes the slice name, the project, and the authority that issued the slice.  This means that experimenters could request two slices with the same name from two different authorities, but the slice URNs would be unique because they were issued by different authorities.  

In practice, you should just know that a given project can only have one slice with a given name at a time.