Installation Press Tab issue

"When the blue SSEC SDI Installer screen appears, select the appropriate option for your system and press Enter. The options are: Install SSEC SDI system or Upgrade SSEC SDI system "

Problem/comment: There is also a "Press tab to edit options" choice. What is this? I tried it but it nothing came up like an editor or choices. I'm not sure what it did - possibly just the upgrade step but it took 11 min 31 sec while Upgrade test without hitting the tab option took 16 min 38 sec