Dependency Model
  When operating on system data, constraints and/or dependencies present are:
  
    - When enabling NIS, nis client must be enabled.
- Package XYZ requires user.
- When configuring PPP, select from list of configured modems.
Some of these dependencies can be coded into the CLAM; some cannot. COAS supports different mechanisms by which these can be implemented:
    - Calling other CLAMs, e.g., call hardware.modem.selectModem().
- Action routines: these action routines can be tied to individual data nodes and are invoked when committing data back to system files.
- Pre-commit verify (e.g., really delete this user abc?)
- Pre-commit actions (e.g., take removed IP interface down now?)
- Post-commit actions (e.g., populate home directory of new user)
  
  
  
  
  
  
  
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