FreeBMDFreeBMD District Aliasers' Reference Page

Welcome to the FreeBMD District Aliasers' reference page. This page should provide the definitive definition of the contents of the district map data files. This page is based on emails from Dave Mayall.

What is the format of an entry for a district?

London City is used here as a test case, as most of the features are used in that one district.

City of London+LND-MDX+clon+1837+3+1869+4+2+1c|

Name of District is first followed by "+"
Then comes *all* the counties that are covered, so searching for London or Middlesex will find entries from this district (notice that "-" separates counties and "+" terminates the field)
The next bit (clon) is used in the link to the district info along with the first county shown(lon.html#clon)
The next 4 entries are opening year/qtr and closing year/qtr
Finally we have 1837-1851 volume and 1852-1946 volume (there will be further fields added later here)
a "|" terminates the basic information, and a series of aliases follow all separated by "|"

C.London|City London|C London|C. London|Central London|CLondon|%London Cty|!Lowden|!Sondon|!Lendon|%London City|%London C|%London%2|%London%1c

In the alias list;
"!" before an entry means this is a spelling mistake
"%" before an entry means "only use this alias if the quarter is correct", so an entry of "London C" in 1870 would NOT alias to City of London (it would actually alias to "London City")
"%" at the end of an entry followed by a volume number means "only use this alias if the volume number also matches". So an entry for London in 1870 volume 1c will match, whilst an entry for the same date in 1a will not.

If using both "!" and "%" at the start, use the "!" first.

We try to avoid using the "%" unless it is absolutely necessary (it creates quite an overhead on the processing).

What is the algorithm to construct the district-map file?

  1. Strip all "?" characters from the transcribed district
  2. Strip all leading and trailing space from the transcribed district
  3. Convert the remaining characters to lower case
  4. Look in the alias table for any matching %district% entries
  5. [if not found] Look in the alias table for any matching %district entries
  6. [if not found] Look in the alias table for any matching district% entries
  7. [if not found] Look in the alias table for any matching district entries
  8. [if not found] Add the stripped lower case spelling as a new variant

What are invalid values for Registration Districts / aliases?

These are described as the first 2 steps of the algorithm to construct the district-map file. The Perl code for this reads:-

     $district=~s/\?//g;
     $district=~s/^\s+//;
     $district=~s/\s+$//;
     my $lcd=lc $district;

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