dtddiff

dtddiff list the changes that have occured in a DTD. dtddiff will output the following information:


Usage

dtddiff is invoked from the Unix shell as follows:

% dtddiff [options] olddtd newdtd

The following are the list of options available:

-compact

Generate a compact listing.

-help

Print a brief usage description. No other action is performed.

-mapfile filename

Use filename as the file for mapping public identifiers and external entities to system files. The default is "map.txt". See Resolving External Entities for more information.


dtddiff Example Output

Here is an example output generated by dtddiff (with the -compact option specified):

    ----------------------------------------------------------------------
                New Elements/Attributes (sgm/html2.0/html.dtd)
    ----------------------------------------------------------------------
        <a sdapref>                      <address sdaform>
        <address sdapref>                <b sdaform>
        <blockquote sdaform>             <br>
        <br sdapref>                     <cite sdaform>
        <code sdaform>                   <dd sdaform>
        <dir sdaform>                    <dir sdapref>
        <dl compact>                     <dl sdaform>
        <dl sdapref>                     <dt sdaform>
        <em sdaform>                     <form>
...

    ----------------------------------------------------------------------
                Old/removed Elements/Attributes (sgm/html.dtd)
    ----------------------------------------------------------------------
        <dfn>                            <key>
        <link name>                      <u>
    ----------------------------------------------------------------------
                           Content Rule Differences
    ----------------------------------------------------------------------
         ------------------------------------------------------------
                                      <A>

  << old content rule <<
  (#PCDATA|img|em|tt|strong|b|i|U|code|samp|kbd|KEY|var|DFN|cite)

  >> new content rule >>
  (h1|h2|h3|h4|h5|h6|#PCDATA|a|img|br|em|strong|code|samp|kbd|var|cite|tt|
   b|i)*
  -(a)

         ------------------------------------------------------------
                                   <ADDRESS>

  << old content rule <<
  (a|#PCDATA|img|em|tt|strong|b|i|U|code|samp|kbd|KEY|var|DFN|cite|p)+

  >> new content rule >>
  (#PCDATA|a|img|br|em|strong|code|samp|kbd|var|cite|tt|b|i|p)*

...

The "..." represents text that has been deleted in order to save space.

If the -compact option is not specified, then each listing in the New Elements/Attributes and Old/removed Elements/Attributes is on its own line.


Resolving External Entities

dtddiff provides the capability of resolving external entities to system files via the -mapfile command-line option. The map file, or catalog, provides you with the capability of mapping public identifiers to system identifiers (files) or to map entity names to system identifiers.

Note
The term "map file" was introduced by the first version of dtddiff. However, since version 1.1.0, the "map file" format has changed to following similiar conventions of SGML catalogs (as defined in SGML Open Draft Technical Resolution 9401:1994). Therefore, the term "map file" and "catalog" are the same in the context of this document.

Catalog Syntax

A catalog contains a sequence of the following types of entries:

PUBLIC public_id system_id

This maps public_id to system_id.

ENTITY name system_id

This maps a general entity whose name is name to system_id.

ENTITY %name system_id

This maps a parameter entity whose name is name to system_id.

Syntax Notes

Example catalog file:

        -- ISO public identifiers --
PUBLIC "ISO 8879-1986//ENTITIES General Technical//EN"            iso-tech.ent
PUBLIC "ISO 8879-1986//ENTITIES Publishing//EN"                   iso-pub.ent
PUBLIC "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN"  iso-num.ent
PUBLIC "ISO 8879-1986//ENTITIES Greek Letters//EN"                iso-grk1.ent
PUBLIC "ISO 8879-1986//ENTITIES Diacritical Marks//EN"            iso-dia.ent
PUBLIC "ISO 8879-1986//ENTITIES Added Latin 1//EN"                iso-lat1.ent
PUBLIC "ISO 8879-1986//ENTITIES Greek Symbols//EN"                iso-grk3.ent 
PUBLIC "ISO 8879-1986//ENTITIES Added Latin 2//EN"                ISOlat2
PUBLIC "ISO 8879-1986//ENTITIES Added Math Symbols: Ordinary//EN" ISOamso

        -- HTML public identifiers and entities --
PUBLIC "-//IETF//DTD HTML//EN"                                    html.dtd
PUBLIC "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML"          ISOlat1.ent
ENTITY "%html-0"                                                  html-0.dtd
ENTITY "%html-1"                                                  html-1.dtd

Environment Variables

dtddiff also supports envariables (ie. environment variables) to aid in resolving external entities. The following envariables are used by dtddiff:

P_SGML_PATH

This is a colon (semi-colon for MSDOS users) separated list of paths for finding catalog files or system identifiers. For example, if a system identifier is not an absolute pathname, then the paths listed in P_SGML_PATH are used to find the file.

SGML_CATALOG_FILES

This envariable is a colon (semi-colon for MSDOS users) separated list of catalog files to read. The file specified by -mapfile is read first before any files specified by SGML_CATALOG_FILES. If a file in the list is not an absolute path, then file is searched in the paths listed in the P_SGML_PATH and SGML_SEARCH_PATH.

SGML_SEARCH_PATH

This is a colon (semi-colon for MSDOS users) separated list of paths for finding catalog files or system identifiers. This envariable serves the same function as P_SGML_PATH. If both are defined, paths listed in P_SGML_PATH are searched first before any paths in SGML_SEARCH_PATH.

The use of P_SGML_PATH is for compatibility with earlier versions of dtddiff. SGML_CATALOG_FILES and SGML_SEARCH_PATH are supported for compatibility with James Clark's nsgmls(1).

Note
When searching for a file via the P_SGML_PATH and/or SGML_SEARCH_PATH, if the file is not found in any of the paths, then the current working directory is searched.

Availability

This program is part of the perlSGML package; see <URL:http://www.oac.uci.edu/indiv/ehood/perlSGML.html>


Author

Earl Hood <ehood@convex.com>
CONVEX Computer Corporation
3000 Waterview Parkway
P.O. Box 833851
Richardson, TX 75083-3851

Phone: (214) 497-4387
FAX: (214) 497-4500

dtddiff 1.1.0