# 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.
PDF
  Siag can save in Adobe's "Portable Document Format". Requires the program ps2pdf.

## 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.