Vensim models in .mdl format are plain text files. While this makes them easy to archive, it can have some unexpected side effects when making them available to other people. There are a couple of things to be aware of when emailing or putting these models on web sites.
Some email programs will automatically wrap lines in text attachments. This can cause problems when those line wraps occur in the middle of a variable name or in the sketch definitions. The typical symptom of this is either a syntax error message, or sketch views that are clearly incomplete. If you open the file in a text editor (such as notepad) you should be able to see where line breaks are added. To prevent this type of problem you may want to zip files before sending them to people.
Sometimes, text files placed on a web site get an extra blank line added between every line. This is typically because of incompatibility in text file formats between Unix, Windows or Macintosh file systems. It is a good idea to check the files you put up on a web site to see if this is a problem. Similar problems sometimes occur when text attachments to email open in a web browser. Try to save the attachment to see if this works better.
Both of these problems can be avoided by publishing the model to a model package.
