Projections allow you to select which aspects of the entries are shown. They usually represent the columns in a report.
A column (projection) is a string of one of the following forms
file state header tag:<tag-name> property:<property-name> timestamp:<timestamp-name> ancestor:<projection>
A column with whether the entry has the 'toast' tag:
A column with the value of the 'effort' property:
A column with the value of the 'DEADLINE' timestamp:
A column with whether the entry has an ancestor with the 'toast' tag: