Spo extension stands for the file before Spss 16. You can try to open spo files with Spss 15 and Spss viewer.
SPO is a file which saved by old versions of SPSS statistical program. Spss 16 and 17 cant open this file format.
If you convert this file to spv extension, you can open with the new versions. Spo files can be also opened by SPSS Leagacy Viewer software.
You may download this one free from the following links.
What to use SPO
SPSS 15 , Spss Viewer
which page related to SPO file
SPO Related Searches
You can check related links about SPO fileextension.