Metacat

<!--

       '$RCSfile$'

       Copyright: 2000 Regents of the University of California and the

                  National Center for Ecological Analysis and Synthesis

     For Details: http://knb.ecoinformatics.org/

        '$Author: jones $'

          '$Date: 2001-10-22 09:46:55 -0700 (Mon, 22 Oct 2001) $'

      '$Revision: 853 $'

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

-->

<!-- EML DTD document that defines the structural

     characteristics of physical objects -->

<!-- The root element, which contains an identifier and 

     an physical description -->

<!ELEMENT eml-physical (identifier, format, characterEncoding?, size?, authentication*, compressionMethod?, 

                                         encodingMethod?, numHeaderLines?, recordDelimiter?, maxRecordLength?, 

                                         quoteCharacter*, literalCharacter*, (fieldStartColumn?, (fieldDelimiter | fieldWidth))* )>

<!-- File identifier of the metadata document -->

<!ELEMENT identifier (#PCDATA)>

<!ATTLIST identifier

  system CDATA #IMPLIED

>

<!-- size -->

<!ELEMENT size (#PCDATA)>

<!ATTLIST size

  unit CDATA "bytes"

>

<!-- Authentication value and method -->

<!ELEMENT authentication (#PCDATA)>

<!ATTLIST authentication

  method CDATA #IMPLIED

>

<!-- Entity format (e.g., text, name of various binary formats [TIFF]) -->

<!ELEMENT format (#PCDATA)>

<!-- characterEncoding fro text files (e.g., ASCII, UTF-8) -->

<!ELEMENT characterEncoding (#PCDATA)>

<!-- Method of compression -->

<!ELEMENT compressionMethod (#PCDATA)>

<!-- Method of encoding -->

<!ELEMENT encodingMethod (#PCDATA)>

<!-- The character used to delimit records in the entity -->

<!ELEMENT recordDelimiter (#PCDATA)>

<!ELEMENT maxRecordLength (#PCDATA)>

<!-- The character used to delimit quote data values so that the

     filed delimeters can be used in the data value, typically

     " or ' -->

<!ELEMENT quoteCharacter (#PCDATA)>

<!-- The character used to escape special characters

     so that they are interpreted literally, usually \  -->

<!ELEMENT literalCharacter (#PCDATA)>

<!-- Number of header lines or information that prepares data -->

<!ELEMENT numHeaderLines (#PCDATA)>

<!--

                        Variable width format fields (attributes) can vary in their 

                        field length, thus the end of the field is 

                        delimited by a special character called a 

                        field delimiter (typically a comma or a space).

                        Data sets are generally classified as fixedWidth

                        format or variableWidth format, but we have

                        determined that this is actually a per-field

                        classification because one may encounter

                        fixedWidth fields mixed together in the same

                        data file with variableWidth fields.

                        In our encoding scheme, the start of each field

                        is assumed to be the column after the last column

                        of the previous field, or the first column

                        if this is the first field in the dataset, unless 

                        the starting column is explicity enumerated using the

                        "fieldStartColumn" element.

                        The end column for each field is classified

                        using either a special character delimeter indicated

                        using the filedDelimiter element,

                        or a fixed field length indicated by using the "fieldWidth"

                        element.  The delimiter for the last field in the data set can be omitted.

                        variableWidth fields can vary in their field length, and the end of

                        the field is delimited by a special character

                        called a field delimiter, usually a comma or

                        a tab character.  fixedWidth fields have a set

                        length, and so the end of the field can always

                        be determined by adding the fieldWidth to the

                        starting column number.  Here is an example:

                        Assume we have the following data in a data set:

                        May,100aaaa,1.2,

                        April,200aaaa,3.4,

                        June,300bbbb,4.6,

                        The metadata indicating the physical layout of the 4 fields would include the 

                        following:

                          <delimiter>,</delimiter>

                          <fieldWidth>3</fieldWidth>

                          <fieldWidth>3</fieldWidth>

                          <delimiter>,</delimiter>

                        In a strictly fixed format file, the metadata would be slightly different:

                        May100aaaa1.2

                        Apr200aaaa3.4

                        Jun300bbbb4.6

                          <fieldWidth>3</fieldWidth>

                          <fieldWidth>3</fieldWidth>

                          <fieldWidth>4</fieldWidth>

                          <fieldWidth>3</fieldWidth>           

                        or, one could explicitly describe the starting columns:

                          <fieldStartColumn>1</fieldStartColumn>

                          <fieldWidth>3</fieldWidth>

                          <fieldStartColumn>4</fieldStartColumn>

                          <fieldWidth>3</fieldWidth>

                          <fieldStartColumn>7</fieldStartColumn>

                          <fieldWidth>4</fieldWidth>

                          <fieldStartColumn>11</fieldStartColumn>

                          <fieldWidth>3</fieldWidth>                   

-->

<!ELEMENT fieldStartColumn (#PCDATA)>

<!ELEMENT fieldDelimiter (#PCDATA)>

<!ELEMENT fieldWidth (#PCDATA)>

<!-- End of file -->