File Formats
Siag has support for these file formats:
- Siag
	
- Native Siag format, with support for Scheme and C-style
		expressions as well as formatting attributes (fonts,
		widths and so on). Very nice for Siag documents, but
		totally incompatible with anything else.
- Comma Separated Values
	
- Almost every spreadsheet can
		load and save this format, but all expressions are
		lost. Despite its name, any character can be used
		as field separator.
- Plain Text
	
- Every line is loaded as a label and placed in column 1
		of successive rows.
- Lotus 1-2-3
	
- Siag imports documents in Lotus Worksheet format and
		can save values in the same format.
- Postscript
	
- Siag can output pretty decent Postscript code, with
		DSC comments and all to make the resulting files
		post-processable. Normally, this code goes straight
		to the printer or to Ghostview for previewing, but
		it can also be saved in a file. Siag cannot load
		Postscript files.
- HTML Tables
	
- Hypertext Markup Language as featured on the World Wide Web.
		A spreadsheet maps nicely to the HTML table format,
		and Siag can save and load (well-behaved) documents
		in this format.
- Scheme Code
	
- Files containing Scheme code can be loaded and evaluated.
- Troff Tables
	
- Tables which can be processed by tbl to produce input
		to the troff document formatting system.
- LaTeX Tables
	
- Tables which can be included in documents using the
		LaTeX typesetting package.
- Excel
	
- Very incomplete support for MS Excel (loading only).
		This requires the xls2csv utility which is not
		part of Siag.
		A better way to convert Excel files to Siag is to save them
		as Lotus worksheets (see below) in Excel and then load
		them in Siag.
Adding Format Handlers
Siag can use external converters to convert files from formats it
can't handle directly to ones it does handle. The converters are registered
by the function register-converters; see siag.scm for the default
implementation of that function.
Ulric Eriksson - June 1999 - ulric@siag.nu