"How do I tell what Terrain Database I have? 

And what happens if I fly out of the coverage on the Terrain Database."  

The terrain data is identified by LAT/LON on the Status Page under the Navigation Data and Obstruction Data. 
               For example: Coverage = N30W045 - N74E059 

There are 9 different Terrain Database selections which cover the world as shown in the two illustrations:

• Africa terrain (S60W030 to N30E060)

• Europe terrain (N30W045 to N75E060)

• Middle East terrain (N00E030 to N45E090)

• Northeast Asia terrain (N45E060 to N75E179)

• South America terrain (S75W179 to N30W030)

• South Pacific terrain (S75E060 to N00E179)

• Southeast Asia terrain (S10E080 to N55E179)

• North America terrain w/ Inland Water 
  (N40W179 to N69W51)

• Central and North America terrain w/ Inland Water 
  (N10W161 to N63W51)

For speed and redundancy, the terrain databases are stored in all displays on removable cards which can be changed by an avionics shop or your airframe mechanic. For example, all of North America is stored on a single card for seamless terrain depiction from Anchorage, Alaska to the Bahamas and from Hawaii to Greenland .

If flying to another region of the globe, the terrain card may be replaced at some point along the route. Flying beyond the boundaries of the terrain database will result only in the loss of terrain-related functions like TAWS and will be indicated by a red “X” through the word "Terrain" on the MFD. Terrain databases are updated infrequently as new information becomes available. Eventually the terrain databases will be consolidated with the world on one large card.

"Why is my identifier not in the database? 

I think it used to be there, and it is there in my Garmin 530. 

What happened to it and what should I do?" 

Chelton Flight Systems EFIS is certified under TSO-C146a for PRIMARY flight navigation. This means we use WAAS GPS for navigation. Unlike Garmin, Honeywell and other navigation systems certified under TSO-C129a for supplemental navigation only, Chelton navigation data must meet the highest reliability standards. 

As of Q2 2006, CFS converts 166 known datums to WGS-84, the standard World Geodetic System locations. The only datum Chelton will not convert or incorporate into our navigation system is "U/Unknown." This is a safety issue. If we are not 100% sure where a navigation waypoint is, then we cannot show it.  Please report "missing" airports to Jeppsesen: navdatatechsupport@jeppesen.com

TSO-146 (WAAS GPS) Directs up to use DO-229C (Minimum Operational Performance Standards for Global Positioning Systems/Wide Area Augmentation System Airborne Equipment). The database requirements fall in a number of sections of this document for example: 
Section 2.2.15 Database Requirements. Subsection 2.2.1.5.2 Content. Under the notes section, note 1 states: “It is recognized that many datums exist other than WGS-84 and that conversions exist between various datums. However, datums and conversions other than WGS-84 cannot be approved without determining acceptable datum equivalency to WGS-84. It is the responsibility of the approving authority to determine if an alternate datum is equivalent.” 

Since CFS cannot determine the datum to convert to WGS-84 then the data cannot be converted and used.

The workaround is to mark the airport as a user waypoint and thus it becomes a "known" point. You may add a waypoint in three ways: Latitude and Longitude, Radial and Distance or Overfly (Designate). These are covered in the Pilot's Guide in Section 5 - Step by Step Procedures, Create a User Waypoint.