Validate 7.2.1, 7.2.2, 7.2.3, 7.2.4 and 7.2.5.
Remove a useless skinparam.
Write 7.2.6 and 7.2.7.
Split into files.
Write 7.2.8.
Write 7.3.
Write introduction of 7.2.
Fix typos.
Fix a typo.
Write the summary.