It looks like two products overlap: Apex Visual force and Oracle Application Express (APEX).
The following questions both have the same tag apex:
closed as off-topic by animuson, lostsock, ɥʇǝS, Monica Cellio, Shadow Wizard Jul 14 at 21:32
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I'm not a subject expert, but as far as tags go, it sounds like they should be disambiguated into something like apex-visualforce (there is already visualforce which should also be removed), and oracle-apex.
For the questions related to the following two products of http://www.salesforce.com:
I'm suggesting the two appropriate tags:
The former is not used. The latter is already used by a number of questions.
As there's already salesforce, I feel that it's a good idea to use it in combination with one of the above or either tags.
This way the products of two companies obviously don't overlap.