# Convert Files from DAT to DATA¶

## Overview & comparison of file types¶

AIMMS 3.0 stores cases were in so-called “data manager files”. AIMMS 3.12 introduced the .data format as an alternative.

This change was made for several reasons.

• Data manager files (.dat) became difficult to manage when maintaining several cases.
• Case files (.data) avoid the risk of data corruption in one case affecting other cases stored in the same file.
• Storing multiple case files in a folder makes it easy to copy cases from multiple users in the same folder, and compare scenarios. (See the AIMMS User’s Guide, Section “Managing multiple case selections”.)

In projects created with AIMMS version before 3.14, a single data manager file (.dat) contains zero, one or more cases. From AIMMS version 3.14, a case file (.data) only stores one case, but multiple cases may be stored in the same folder.

 Before AIMMS 3 AIMMS 3.14 and later .dat .data Single data manager file contains zero, one or more cases Disk files and folders store multiple files, with one case per file

The default location of .data files, is the data subfolder of the project folder. (You can modify this with the project option Default data folder.)

When upgrading AIMMS on a particular project, the data management style persists. In other words, using AIMMS 3.12 on a project created using AIMMS 3.11, will still use as “data management style”: “Single data manager file”. This allowed users to use their data in data manager files created with older versions of AIMMS.

For these upgraded projects, the data management style can be changed; it is a setting of the project:

After changing this setting; AIMMS needs to be closed and re-opened before the change takes effect properly. (Just closing and re-opening the project is not sufficient).

After restarting AIMMS, the cases in data manager files can be extracted, by the dialog opened via:

but it now looks different:

Last Updated: October, 2019