Observed:
BINTOC(somenumber,"F") is BINTOC(somenumber,"FS")

CLEAR

? 0h+BINTOC(1.0,"F")
? 0h+BINTOC(1.0,"FS")

Result, "F" is unusable in index
otherwise from how much writing in the documentation:


When using BINTOC( ) for an 8 byte index creation, you should use 8 and not "B". For 4 byte results, you should use 4 if nExpression is an integer type. Otherwise, you should use 'F' for floating point type.


Repro:

CREATE CURSOR TESTX (FREAL B)
INSERT INTO TESTX VALUES (1)
INSERT INTO TESTX VALUES (2)

INSERT INTO TESTX VALUES (-1)
INSERT INTO TESTX VALUES (-2)

* INTERPRETER FREAL like a Real floating point
INDEX ON BINTOC(FREAL,"F") TAG TREAL
BROWSE NORMAL TITLE "WRONG ORDER"

INDEX ON BINTOC(FREAL,"F") TAG TREAL DESCENDING
BROWSE NORMAL TITLE "WRONG ORDER"

USE
RETURN