2.6. Filters
2.6.1. Introduction
A filter controls how a block of text is interpreted. The text is usually delimited by block and endblock macros.
For example, tables are usually defined via the table filter:
!block table Option Description -h display help -o specify the output extension !endblock
The result is:
| Option | Description | 
| -h | display help | 
| -o | specify the output extension | 
2.6.2. Commonly used filters
Some of the commonly used filters are:
| Filter | Description | 
| table | the lines are a table in SDF's TBL format | 
| example | the lines are example paragraphs | 
| title | used to build a title block for memos, faxes, etc. | 
| topics | include files as sub-topics | 
| appendix | replace H1 styles with A1, etc. | 
| plain | replace H1 styles with P1, etc. | 
A complete list of the supported filters and their parameters is given in the SDF Reference manual.
2.6.3. Other macros supporting filters
Other macros also support filters. These include:
For example, the following line includes another SDF file and formats it as an appendix:
!include "tips.sdf"; appendix
Note: The appendix and plain filters enable authors to construct topics without needing to worry about how those topics will be used, e.g. a topic may be a chapter in one document and an appendix in another!
