Each family of time series in the Z.1 is assigned a nine-digit numeric identifier by the FRB, and each series has a two-letter prefix.  A series appears as a numbered line item in one or more tables.  The tables regularly undergo these types of change:

1. Add series - Line item numbering changes
2. Delete series - Likewise
3. Change the method of calculation for a series - Assign a new ID
4. Renumbering of a table
5. Addition or deletion of tables to reflect changes in sector and instrument categories

Note that in situation (3), the prior series will be discontinued by FRB, and you will need to edit baskets to use the new series.  The replacement series always contains a complete history.

The Data Buffet catalog tree is not always synchronized with the FRB's table layouts, but will always contain all series reported as part of the Z.1  You can retrieve new series directly because their mnemonics are based on the Z.1 numeric identifiers.  The IDs appear in the "coded tables," available as PDFs online: ( http://www.federalreserve.gov/releases/z1/Current/Coded/ ).  For instance, the series FL894104005 from table L.1 is named XZFL894104005Q.IUSA in DataBuffet.com.  The nine-digit code is copied directly, and the two-letter prefix is translated as follows:

Note that a small number of series are computed by Moody's Analytics.  To support our Consumer Précis product, we compute smoothed versions of the quarterly series from the B.101 balance sheet table (originally B.100).  These have the prefix ZFL· (in U.S. mnemonics, "Z" usually means seasonally adjusted, but not here).

Quarterly series will have the concept code suffix ·Q, annual series have ·A, and all series have the geo code .IUSA.

As of the 2010Q1 release (June 10, 2010), all newly-added series are immediately configured with the correct description, because it is available as metadata in the FRB's bulk data files.  Previously we had to manually locate the series in the coded tables and derive a description ourselves.