Recognized META information in HTML documents

Introduction

As the ht://Dig system will index all HTML pages on a system, individual authors of pages may want to control some of the aspects of the indexing operation. To this end, ht://Dig will recognize some special <META> tag attributes. The following things can be controlled in this manner:

  • Do not index the document
  • Notify a user that the document has expired
  • Set keywords for the document

General <META> tag use

In HTML, any number of <META> tags can be used between the <HEAD> and </HEAD> tags of a document. There are three possible attributes in this tag, two of which are recognized by ht://Dig:

NAME
Used to name a specific property.
CONTENT
Used to supply the value for a named property.

A document could start with something like the following:

<HTML>
<HEAD>
<META NAME="htdig-keywords" CONTENT="phone telephone online electronic directory">
<META NAME="htdig-email" CONTENT="pat.user@nowhere.net">
<TITLE>Some document title</TITLE>
</HEAD>
<BODY>
Body of document
</BODY>
</HTML>

Recognized properties

The following properties are recognized by ht://Dig:

  • htdig-keywords
  • htdig-noindex
  • htdig-email
  • htdig-notification-date
  • htdig-email-subject
  • robots
  • keywords
  • description
  • author

Detailed information about the htdig-email, htdig-notification-date, and htdig-email-subject properties can be found in the Email notification service document.

Descriptions of the properties and their values:

htdig-keywords
The value of this property should be a blank separated list of keywords which will get a very high weight when searching. This can be used to get around some problems with common synonyms for words in the document. For example, if a document is a telephone directory, possible keywords could be "telephone phone directory book list". Now, regardless of what text is actually in the document, it can be found if these keywords are used in the search. The weight that words in the content string will have in search results is controlled by the keywords_factor attribute in your configuration.
htdig-noindex
This property has no value associated with it. If it is used, the document will NOT be included in any searches. Example uses of this could be:
  • A document which is dynamic. ie: the contents change continually.
  • Temporary document, not officially available, yet.
  • A document you just don't want to be found.
htdig-email
The value is the email address a notification message should be sent to. Multiple email addresses can be given by separating them by commas. If no email address is given, no notification will be sent.
(Please check the Email notification service documentation for more details on this.)
htdig-notification-date
The value is the date on or after which the notification should be sent. The format is simply month / day / year, or if the iso_8601 attribute is set, year - month - day. Make sure that the year has the century with it as well. This means that you should use 1995 instead of 95.
If no date is given, no notification will be sent. (Please check the Email notification service documentation for more details on this.)
htdig-email-subject
The value specifies the subject the notification message. This is an optional property. (Please check the Email notification service documentation for more details on this.)
robots
The value specifies restrictions on robots (including ht://Dig) for the current page. These restrictions can be "noindex" to prevent indexing the document but allowing the robot to follow links from the page, "nofollow" to allow indexing but preventing links from being followed, or "none" to prevent both. Additionally, ht://Dig supports the values "index" and "follow" and "all" which obviously are the opposite of the other values and are the default behavior. For more information on META robots tags, check out the HTMLAuthor's Guide to the Robots META tag.
keywords
The value of this property should be a blank separated list of keywords, just as for the htdig-keywords property. They are treated as equivalent by htdig. The reason for two different properties is that the keywords property is used by other search engines as well, while the htdig-keywords property can be used for words you want indexed only by htdig. You can get htdig to treat other property names as equivalent to htdig-keywords, or disable the htdig-keywords or keywords properties, by changing the keywords_meta_tag_names attribute in your configuration.
description
The value allows you to specify an alternate excerpt (description) of a page. If the config-file attribute use_meta_description is used, then any documents with descriptions will use them instead of the automatically generated excerpts. The weight that words in the content string will have in search results is controlled by the meta_description_factor attribute in your configuration.
author
The value specifies the name, email address and/or affiliation of the creator or authoriser of a page. The weight that words in the content string will have in search results is controlled by the author_factor attribute in your configuration. A search for "author:name" will look only in these fields for the word name.

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