Thank you Jim. I appreciate the help. Part of what I don't understand is what appears to be inconsistency. My error report consisted of about 4500 lines. I did some counts of the occurence of certain tags in both the input GEDCOM file and the error list. A level 1 OBJE tag occurs 548 time in the input file but is flagged 61 times in the error file. In all those cases it says "Warning : Unknown level 1 tag (skipped)." For the CHAN tag there are 2009 occurences in the input file but only 298 are flagged as errors. Both CHAN and OBJE are valid level 1 tags. PEDI tag is valid for GEDCOM 5.5 and seems to be rejected on import.
Some of the errors I can accept. Certainly the use of special tags that are preceded with the _. However, this GEDCOM file has been imported into PhpGedView without error, into The Complete Genealogy Reporter without error, and into several other programs with only a few minor or no errors.
Also, I don't understand the "Details" window showing a number of line entries with "Unknown GEDCOM tag: " and NO indication of what tag is unknown. This makes it very difficult to correct the line item error since I have no way to relate the two. In all these cases it seems to have something to do with the spouse. However, since there doesn't appear to be enough information to correct the problem.
The file I'm trying to import is created using Family Historian. That program adheres fairly closely to GEDCOM standards. They do have some quirks such as using _FILE instead of FILE tag. Those variations I am able to manage using a text editor and doing some global changes.
I would appreciate some guidance on handling these inconsistencies.