This is a message that should always worry you. It means that graphics are being controlled by tag index with blank tagnames (except in OIS 20 and MCS systems, of course). This is dangerous because maintaining a correct set of tag index values proves difficult over the long run.
DBDOC has techniques for finding and eliminating blank tagnames.
--Scanning graphic AACRT003.DIS Tag index not found: 20640.
Consider the example message:
Tag index not found: 20640.
This means that a display element references a blank tagname with tag index 20640, but no tag with index 20640 was found in the database. That part of the graphic simply does not work. DBDOC cannot tell you what tag index 20640 is supposed to be. You have to find that in your archives. The message tells you that the tag index is used in at least one graphic, and it does not exist in the database.
However, searching for places that the undefined tag TAG_20640 is used might be useful. In the image, that is not the case, because you can see that the problem is simply in a trend group. If you find the tag index used on a graphic that gives you some additional clues, it might help resolve it. DBDOC links directly to all of them. In the example, you might find that graphic AACRT061.DIS contains enough information for you to identify the problem and correct it.
It is for this reason that DBDOC synthesizes an undefined tag TAG_20356 (in the example) and creates the links to it – it might help sort it out.
In INFI 90, a SODG graphic can be controlled either by the tagname or the tag index.
The latter method (tag index) is the only way for OIS 20 and MCS consoles to display graphics. For these graphics, the tag index MUST relate to an entry in the tag database that is meaningful. In those old systems, graphics could be cloned by directly changing the tag index, so that it was no longer related to the tagname in the graphic .DR (or symbol .DY) file. This resulted in many graphics and symbols with mismatched tag names and index values.
In the case of Conductor VMS, WinLDG (WinTools SODG graphics) and PCView / LAN90, the tagname is the correct key to what is displayed. In fact, in PCView / LAN90, the tag index has no meaning as a concept.
When tag index keyed versions of SODG graphics were upgraded, and the tagname did not match the tag index in the .DR or .DY file, some procedures blanked the tagname. From that point on, only the tag index was in the file to tell what tag to display at that position.
The tag index, however, is subject to reindexing. If this is done, any graphic using tag index only will be affected negatively.
Note, also, that even a few of these errors might show you that a serious problem exists. If index values are not correct for a few that come out here, it can mean that many more values are wrong. There is no message because the tag index points to a tag that exists, but that tag is no longer the correct one. Consider a simple example with tag index values 2 to 5000 in use. If the index values get corrected to be 1 to 4999, all graphics will have been broken.
This error can be built directly into Hyperview. For more information, see the article Building error reports into the M14.