FlyBase:Identifiers

FlyBase Identifier Numbers

FlyBase assigns unique identifier numbers to several classes of object within the database. One reason for this is to allow unambiguous cross-references both within FlyBase and between FlyBase and other databases.

FlyBase identifier numbers have the general form FBxxnnnnnnn where xx is an alphabetical code for the identifier class and nnnnnnn is a ~7 digit number, padded with leading zeros. Some data classes, such as FBsf, use more than 7 digits.

The following classes of object are now publicly available in FlyBase data:

Data Class	Description
FBab	aberration
FBal	allele
FBba	balancer/genotype variant
FBcl	clone
FBgn	gene
FBim	image
FBig	interaction
FBlc	large dataset metadata
FBmc	molecular construct
FBms	molecular segment
FBpp	polypeptide
FBrf	reference
FBsf	sequence feature
FBst	stock
FBtc	cell line
FBti	transposable element insertion
FBtp	transgenic construct or natural transposon
FBtr	transcript

Each object has a single Primary identifier number that is used to uniquely identify it in the database.

An object may also have any number of Secondary identifier numbers. If an object has a secondary identifier number, it generally indicates that at some point an entry has been merged with or split from other entries in the database. This may have occured due to more data becoming available in the literature or due to correction of previous errors in the database.

The rules for when primary identifier numbers become secondary are complex. Some examples are included below:

A merge:

If two entries A and B are found to refer to the same object, then a new primary identifier number will be given to the merged entry, and the old identifier numbers of entries A and B will be listed under this merged entry as secondary identifier numbers.

A split (case 1):

If one entry is found to correspond to two (or more) objects, e.g., entry A does, in fact, refer to objects X and Y, then X and Y, as new objects, each get new primary identifier numbers and the old primary identifier number of the suppressed entry A is listed as a secondary identifier number under both X and Y.

A split (case 2):

If one entry is found to correspond to two (or more) objects, e.g. entry A refers to objects A and X, then the existing entry for A and the new entry for X each get a new primary identifier number and the old primary identifier number of A is listed as a secondary identifier number under both A and X.

If an object is simply renamed, i.e. its valid symbol in FlyBase is changed without there being a merge or a split, its primary identifier number does not change.

The following classes of identifier were previously used in FlyBase, but are no longer in current use as identifier numbers in the database.

FBan - annotation Cetegory:DONE