project_id
(primary key)

VARCHAR(40)

not null

The ID of the project to which the history element is associated.

sequence_num
(primary key)

BIGINT

not null

The sequence number which determines the ordering of the history element in relation to the other history elements in the same project.

history

VARCHAR(40)

not null

The ID of the related history element in the project whose ID is in the project_id column.