All entities on the DNAnexus platform have a unique ID.
Users and organizations have unique handles, or names, that cannot be changed. For these entities, entity IDs are made out of the entity's class and the handle.
When all other entities are created, they are assigned unique IDs by the system that are also fixed for the lifetime of the entities. These are of the form class-xxxx. The second part (referred to as "xxxx") consists of 24 case-sensitive characters from 0123456789BFGJKPQVXYZbfgjkpqvxyz, e.g.: project-j47b1k3z8Jqqv001213v312j1, or file-47jK67093475061g3v95369p. Note that when a data object is copied from one data container to another, its ID remains the same even though its metadata may change in the different data containers in which it resides.
Apps are special in that they have an associated name under which multiple versions can be published. Each version is also assigned a unique ID of the form "app-xxxx", but it can also be uniquely referred to as "app-appname/alias", where alias can be the version or a tag that the developer has attached to a particular version.
Examples of the entity IDs are provided below.
Format of entity ID
file-47jK67093475061g3v95369p applet-B0VJ0vK4Zg2KbPvQg9fQ000f record-B0FJgXy4Zg231jgbQ9zQ0003
app-xxxx app-apphandle app-apphandle/version app-apphandle/tag
app-9z80yBpyjv967GgZjkz00001 app-bwa app-bwa/1.3 app-bwa/unstable