@DanielaNRW wrote: When you open datasets you cannot change values or the data type because of read access. If you try to change a value a popup window opens and asks if you want to switch to update mode. Now you can change the properties of the column and the drop down menu for Type is not greyed out any more. This does not make much sense.  The only reason to "open" a dataset would be to check the values so you can plan how you want to analyze it.  Do you mean you are trying to treat your data as if it was in an insecure environment like an Excel Spreadsheet?      To work with your data and derive new information to use in your analysis write a program.  Now you know exactly what you did and can recreate it or explain it to others.   To your original issue, if you are reading data from a text file then skip the guessing process and just write your own data step to read the file. Then you have full control over how the variables are defined and how to text into the file is converted into variable in a dataset. ... View more