4abf1b6b_QLite_FTS3_and_FTS4_Extensions__Interpretation
[Column] level [Interpretation] 
Between them, the contents of the "level" and "idx" fields define the relative age of the segment b-tree. The smaller the value stored in the "level" field, the more recently the segment b-tree was created. If two segment b-trees are of the same "level", the segment with the larger value stored in the "idx" column is more recent. The PRIMARY KEY constraint on the %_segdir table prevents any two segments from having the same value for both the "level" and "idx" fields.
SQLite FTS3 and FTS4 Extensions
Interpretation