Forward/backward version compatibility details

Background
There are three components to CPS Utilities: the data and data-related files, the software, and the supporting documentation. The data-related files are all the files that change as the data change, e.g. the documentation pages for each variable, their Appendices, and various indexes and lists. All this material is used by the software in the process of performing its search, display, and extraction functions. The supporting documentation consists of other material which is not used by the software, but is provided as a library of reference items for the user's convenience.

The software is common to all surveys (March, October, Outgoing Rotations, Monthly Basic, etc.).

The data and data-related files are different for each survey.

The supporting documentation includes some common and some survey-specific items. They are accessed by clicking the 'General Documentation' button on the Entry Screen. A secondary window shows, with the common documents on the right, and the survey-specific documents on the left.

On first installation
When CPS Utilities is first installed, the software, the data-related files, and the common supporting documents are always copied from the CD/DVD to the computer's hard disk. The user is offered a choice whether to copy the data files themselves to the hard disk. The user is also offered a choice whether to copy the survey-specific supporting documentation to the hard disk.

Items not copied to the hard disk are accessible only while the correct CD/DVD is in the reader.

Update considerations
Unicon periodically updates the software, to add features or to improve performance. Unicon also routinely adds or revises data files (and updates the corresponding data-related files) when the Census Bureau releases new or revised data. Unicon also may update or augment the collection of supporting documentation items.

When any of these updates is made for a given survey, Unicon always includes the latest software and the latest supporting documentation items on the CD/DVD for that survey. However, discs for other surveys are generally not updated until a change specific to that survey is required.

Users may therefore have discs for different surveys with different software and common supporting documentation update levels. In fact, Unicon may ship new discs for different surveys with different update levels.

Resolution of conflicting update levels
Unicon configures its software upgrades to provide backwards compatibility with earlier versions, and its installation procedures will not replace a later version with an earlier one. Thus a later software version will correctly access a different survey containing an earlier software version, even if the CD/DVD with the later software is installed first.

Similarly, if common supporting documentation items are copied to the hard disk, and a new survey is installed, if the new CD/DVD contains earlier versions of these documentation items, they will not overwrite the later versions.

User's responsibility to properly install updates
On receiving a CPS Utilities CD/DVD with a new year of data for an existing survey, it is not sufficient to just insert the disc and expect the data to be accessible. The updated data-related files, and (probably) new software and common supporting documentation files must be installed too. If the options had been selected to copy data or survey-specific supporting documentation files to the hard disk, they would also need to be updated. The following paragraphs describe how CPS Utilities facilitates this process.

Updating software and other files
The precise software revision of a current installation may be shown by clicking 'Help' in the menu bar of any CPS Utilities screen, and selecting 'About CPS Utilities' from the drop-down menu. The latest available revision is shown here and can be downloaded and installed from there if required. (Even if you're not updating any surveys, you may still want to do that to get the benefits of the latest software).

If your computer allows 'autorun', and the software on your new CD/DVD is a later revision than your current installation, soon after inserting the disc a message will show asking whether you want to update your software from the disc. Click 'Yes'. (If your computer doesn't allow 'autorun', run setup.exe from the root directory of the disc).

When software installation is complete, further screen instructions will guide you through the steps of updating the data-related files, the common supporting documents, and any other files for which you previously selected the option to copy to your hard disk.

Updating other files if software update not required
If the software on your new CD/DVD is not at a later revision than your current installation, autorun will not take place, but you still need to update the data-related files, the common supporting documents, and any other files for which you'd selected the option to copy to your hard disk.

This is accomplished by clicking 'Change Setup' on the menu bar of the CPS Utilities Entry Screen, and then clicking the 'Reload' button located in the left frame.

Discard your old CDs and DVDs
Your old data discs for the same survey may not be compatible with the new data-related files, so be sure to only use the new ones.

For Monthly Series users
Subscribers to the Monthly Basic and Monthly Outgoing Rotations surveys who don't copy the data files to their hard disk may ignore most of the above unless instructed in a cover letter. The software, data-related files, and supporting documentation for these monthly updates do not usually change from month to month.