From The Document Foundation Wiki
How do I open a text file containing separate fields in a spreadsheet? What if there are different field separators?
If your ASCII file is not already named with a .csv or .txt extension, rename it (preferably as .csv).
- Go to ▸ .
- In the File Type box, select: Text CSV ( *.csv; *.txt). (Note : This choice is near the bottom of the list).
- Navigate to your ASCII file and select it.
- Click on Open.
- In the Text import dialog that opens, select the correct Separator options for the columns:
- if there is a separator, choose Separated by and then enter the appropriate separator(s).
- if the columns are fixed width, choose this option and position the column dividers in the preview.
- If you are importing a data file from a stock control system, it is highly probable that the decimal separator will be a dot. In this case set the language to English (US).