Compatibility is an evidence claim, not a similarity score.
Two devices can share pipe sizes and electrical limits and still do different jobs. BecSpec therefore treats specifications as rejection checks, not permission to invent compatibility.
Relationship classes
Direct replacement means the manufacturer explicitly describes the newer product as a replacement or interchangeable product for the legacy identity.
Component successor means the manufacturer explicitly says one component supersedes another component of the same role.
System successor means the manufacturer identifies a newer system configuration for an older system configuration; that does not automatically prove every old component can be retained.
Supported configuration means the manufacturer documents products together, but does not claim one replaces the other.
Not verified means BecSpec has not found adequate OEM evidence for a positive replacement claim.
Product roles stay separate
Pressure controllers, rain-to-mains changeover devices, integrated rain-to-mains controllers, pumps and complete systems are stored as different roles. A pressure controller must not silently become a replacement for a mains-changeover device.
Source sanity checks
Manufacturer pages are not accepted blindly. An apparent successor edge is quarantined when the legacy and replacement product classes conflict unless the source clearly describes a whole-system migration. The seed includes one REEFE example deliberately left quarantined for this reason.
What specifications are allowed to do
Electrical current, pump power, cut-in pressure, connection size and similar specifications can rule out an impossible pairing. They do not create a positive compatibility claim without supporting manufacturer evidence.