If you are using Netscape for the Macintosh to access data files listed below under the bulleted topics "Sequences" and "Alignments", you should use the following procedure for downloading the files.
Use Netscape to follow links to the data file you wish to download (let's say the GenBank file of HPV15, HPV15.gb). The file will appear in your Netscape window.
To make a copy of this file on your local computer do not use the "Save as ..." command located under the Edit menu. If you do, the resulting saved file will not have line breaks; it will appear as one long line with small "square" characters where the line breaks ought to be. The squares are actually "line feed" characters (ascii char 10).
Instead of using "Save as ..." pull down the View menu to "Document Source". This will automatically copy the file to your local machine and launch the program Simple Text to view the file.
Where does the copy of HPV15.gb get saved on your Mac? That depends on how you have set up your Netscape browser. By default, downloaded files are stored in the Mac's System folder. This is not a particularly obvious place for them and you may want to change this location. Here is how to do that. At the top level of your hard drive create a new folder called NETSCAPE_TEMP_FILES (or something). Now, inside of Netscape pull down the Options menu and select "General Preferences ..." A window appears that allows you to set preferences in several categories -- "Appearance, Colors, Fonts, Helpers, Images, Applications, and Languages." Select "Applications". The last line on the Applications window shows the location of your "Temporary Directory." This is where downloaded files are currently being stored. You now wish to change that temporary directory to the NETSCAPE_TEMP_FILES directory you just created on your hard drive. To do this press the Browse button and locate NETSCAPE_TEMP_FILES. Now press the Apply and OK button in the Applications window. From now on all your downloaded files will be stored in NETSCAPE_TEMP_FILES.