There are several areas related to your application, including the "application status" - these are individual records for each time someone has touched your application. They are listed in reverse order (so most recent activity is printed first, to oldest activity printed last). There is a sequential number (most recent to oldest), an indication of the application's status (e.g., open) the reason for that status (e.g., "in process"), decision information (if any), the office where the person touching your file is located, the date of the entry, and the identifier of the CIC person touching your file (in the format "first initial, last initial, five digit identifier).
The "application" area seems to consist of records for changes to the application information itself (e.g., my own notes from last month which show a change of "Primary Office" from "Ottawa" to "Los Angeles". Similar format to the "application status".
Eligibility would say "not started" if they required an interview, because the legitimacy of the relationship is required for Eligibility. In my own notes I see an entry for Eligibility where it went from "in progress" to "passed" and five days earlier it went from "not started" to "in progress".
Some of the entries are redacted. For example my "security" update says the 'old value' was "not started" and the 'new value' is blank, as is the date, but the entry before and after have the same date, so THIS entry must also have the same date and elsewhere the same officer says the application is RFV ("ready for visa").
The notes don't say why they want an interview? It's a bit odd, and a bit rare, but it means they should transfer your file to an office in the US, hopefully the one you requested (NYC, Detroit, Seattle, LA).
There is a thread on here to discuss the meanings of GCMS notes.
I updated what I saw of the spreadsheet, as usual, if I missed anyone, let me know! 
