Yes, the syntax to create a primary key index as a reverse key index is accepted and does have the desired effect. Here is a demonstration.
SQL> create table test (n number, constraint pk_test primary key (n) using index reverse);
Table created.
SQL> select index_name, index_type from user_indexes where table_name = 'TEST';
INDEX_NAME INDEX_TYPE
------------------------------ ---------------------------
PK_TEST NORMAL/REV
Secondly, a reverse key index on a date column is not a good idea, because it
will entirely prevent range scans on the index.
I appreciated your article on reverse key indexes since I am considering using a reverse key index on a primary key field which is a sequence number. Have you created a reverse key index as part of a primary key constraint? The syntax of the CONSTRAINT clause did not specify the option to use REVERSE as part of the USING INDEX clause. How can I be sure that a reverse key index is really created?
Second question... would creating a reverse key index on a date column negatively impact retreval of records that are within a date range (use the BETWEEN date1 AND date2)?