If you are using Microsoft Excel to view or edit the content in a CSV (comma-separated value) data file for use with DesignMerge, you should take care to open the file without automatically changing any of its content. When Microsoft Excel automatically opens a CSV file, Microsoft Excel will convert long numeric data into Scientific Notation data and will also apply the General format to the data inside this file. Applying the General format may apply unwanted changes to the text in the file. For example, this format will remove leading zeros and will also remove zero decimal digits.

To prevent the text from being automatically changed when you open the file in Microsoft Excel, one approach is to apply the Import Data from Data Sources (Power Query) feature if that feature is available in your version of the Excel application. For more details, please refer to this Microsoft Support web page:
Excel Import and analyze data Import data Import data from data sources (Power Query)

For those using newer versions of the Microsoft Excel application, another approach is to create a new Excel spreadsheet file, then open the File menu and choose Import, where you can follow the prompts. For example, indicate the type of file (Comma or Text), and choose the file. This will display the Excel Text Import Wizard where you can indicate the following:

1. On Step 1 of the Text Import Wizard, select Delimited for the Original Data Type, and click Next to continue to the next step.
2. On Step 2 of the Text Import Wizard, select the appropriate Delimiter, uncheck Treat consecutive delimiters as one, and click Next to continue to the next step.
3. On Step 3 of the Text Import Wizard, click on the First Column that is displayed in the Data Preview box. Then, scroll over in the Preview box to the Last Column, press Shift and click on the Last Column. This selects all columns in the  Preview box. With all columns selected in the Preview box, select Text for the Column data format. Confirm all columns are labeled as Text in the Data Preview box, and then click the Finish button.
4. Indicate where to put the data (in which cell within the existing new sheet or in a new sheet). 

If your Microsoft Excel application does not provide the above feature, then follow the steps below:

1. Change the filename extension on the data file to the .TXT filename extension.
2. Start Microsoft Excel, open the MS Excel File menu, choose Open, and select the .TXT data file. This will automatically start the MS Excel Text Import Wizard.
3. On Step 1 of the Text Import Wizard, select Delimited for the Original Data Type, and click Next to continue to the next step.
4. On Step 2 of the Text Import Wizard, select the appropriate Delimiter, uncheck Treat consecutive delimiters as one, and click Next to continue to the next step.
5. On Step 3 of the Text Import Wizard, click on the First Column that is displayed in the Data Preview box. Then, scroll over in the Preview box to the Last Column, press Shift and click on the Last Column. This selects all columns in the  Preview box. With all columns selected in the Preview box, select Text for the Column data format. Confirm all columns are labeled as Text in the Data Preview box, and then click the Finish button.
6. The data file will now be opened in MS Excel and all of the data in this open file will have been formatted as Text (no changes will have been made to the text).