The tracks indicated by a "ball" logo (e.g., ) have been lifted from a previous assembly of the same organism with a minimum of quality-control scrutiny (e.g., have been lifted from hg17 or hg18 to a later human assembly). The number indicated on the logo indicates the version of the assembly that the track was lifted from. These tracks are provided to our users with the intent that they assist in interpretation of other data, but must be used with caution. Not all annotations remain intact when lifted in this manner and in any case, cannot by definition contain any sequence that is new to the newer assembly.

It should also be noted that tracks containing large regions will not lift as well because of the increased chance of spanning a region that has changed between the two assemblies.