What do the abbreviations in the column headers mean?

What do the abbreviations in the column headers mean?

G1, G2, G3 and G4 refer to the site conversion goals specified in the profile settings. The URLs associated with particular conversion goals can be found in the "Content Optimization > Goals & Funnel Processes > Goal Verification" report.

P refers to the pageviews associated with a visit. The "Content Optimization > Content Performance > Depth of Visit" report covers this in detail.

T refers to the transactions posted during a visit. The complete list of transactions recorded can be found in the "E-commerce Analysis > Commerce Tracking > Transaction List" report. If you're not currently tracking transactions, read How do I track e-commerce transactions?