oracle's use of NT Registry

We are a bit confused about some of the uses Oracle makes of the NT Registry. (Well, actually I am confused about a lot of things, most of which have nothing to do with Oracle, but that's a different story! ;-)

Specifically, we're wondering why the same string values appear in HKLM\SOFTWARE\ORACLE and also in HKLM\SOFTWARE\ORACLE\HOME0 -- and, in a multi-home system, in HKLM\SOFTWARE\ORACLE\HOME1 thru HOMEn.

Of particular interest is the use of TNS_ADMIN to point to TNSNAMES.ORA and SQLNET.ORA. We have had some inconsistent results in trying to determine which leaf of the registry is being used. This may be a poor example of the more general question because TNS_ADMIN is not created by default at installation time. But the general question becomes "how does Oracle determine which registry leaf (\ORACLE vs. \ORACLE\HOMEx) it is going to look to for any particular key value?" And as a follow-on question, " if it is always going to look in \ORACLE\HOMEx, why does it bother putting any string values at all in \ORACLE ?

TIA.

--
- Ed Stevens


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