When you save a Prism file, you save the entire project into one file. You have a choice of two file formats:
•PZF format: This is a binary format that can be opened by Prism 4 or later, but not by other applications.
•PZFX format: This is a format that can be opened only by Prism 5 or later. The first part of the file contains all the data tables and info sheets in a plain-text XML format that can be viewed by other programs. After that comes information about results, graphs and layouts in a format that is incomprehensible to any program but Prism.
Advantages of PZFX compared to PZF
•The PZFX format is a bit more secure for long-term backing up. Even without access to Prism, the data in the file are in plain text that can readily be viewed.
•Files saved in PZFX format tend to be much smaller (about 10% the size) than the same file saved as PZF. We recommend that you use PZFX files routinely. Even though PZFX files are almost always smaller, they may be faster or slower than PZF files to save and open, depending on how large your data tables are and whether you included pictures in your graphs or layouts.
•The data (and info and scripts) are in a plain text format at the beginning of the PZFX file. It is possible to create a program that swaps out the saved data with new data. Open that altered file, and the new data will instantly be analyzed and graphed.
Disadvantages of PZFX compared to PZF
•Prism 5 was the first version that understand the PZFX format, so these files cannot be opened by Prism 4.
•Avoid the .PZFX format if you plan to post the file on a web site. Web browsers sometimes detect the XML format, and try to open the file with some program that understands XML rather than opening with Prism. In contrast, .PZF files generally just open in Prism, as they should.
•The PZFX format never contains analysis results, so Prism needs to recompute the results when it opens the file (or when you view those results pages or graphs that depend on them). If your analyses are very slow to recalculate, choose the PZF format with the Compact option turned off (see below). These files will contain analysis results, so Prism will not need to recalculate anything when you open the file.
•With large files, it takes about ten times longer to save or open a PZFX file than a PZF file. This is because the information about graphs and layouts is compressed in PZFX files, and compressing/decompressing can be slow.
Compact PZF format
Prism has an option to save PZF files in compact format. All the compact format does is leave out analysis results. Files with lots of complicated analyses will be smaller if saved in compact form, but all those analyses will need to be recomputed when the file is opened, which can take time. Choose to use, or not use, the compact format in the File tab of Preferences. PZFX files are always saved in the compact format.
Zipping the file with standard zipping software can do a much better job of compression. To really make a PZF file as small as possible, save it compact and then zip it.
Check the box in the Preferences menu if you want to save in compact format as a default.
What if you have both a .pzf and .pzfx file with the same name?
Prism opens the file you ask it to open. It won't even "notice" that there is another Prism file with the same name (except extension). It won't coordinate the two files. We strongly suggest not keeping two files with the same name (but one .pzf and the other .pzfx) as it is too easy to get mixed up and lose work.