Checked following occurrences in comments:
- "Python 2.[456]"
- "Zope 2.[891]"
- "BBB"
- "BACK"

Checked uses of:
- email, hashlib, numpy & tarfile (modules)
- ImportError
- string.Template
- suppress_events (parameter of _setObject)

Excluded:
- some forked modules (MailTemplates, PortalTransforms...)
- some i18n compatibility code