If you try to install OCI (Oracle Call Interface) 7.3 under MacOS 9, the "Applications" folder (into which you install the "ORACLE" folder) becomes a "Package" (refer to the new feature list of MacOS 9) and cannot be opened. This folder contains SQL*Plus and the tools to test and tune the network.
To fix this problem, Apple provides an utility with MacOS 9 that converts a package to folder if needed. The name of this tool is: "Package First Aid Utility"
To use it :
Copy the P.F.A.U. application onto your hard disk
Drag and drop the target package onto the tool
See the result...