Use:
B_Total_Length(B) Amount of bytes in B
or
B_Line_Count(B) Amount of lines

in http://members.fortunecity.com/polarissoft/Products/rFunc/rfunc.html

> You can't test BLOBS for having ''.. it's the same as not being able to test
> blob string comparisons. You can check for NUL or you can use a UDF
> where F_BLOBLEFT(notes,10) =''
> but a straight comparison will not work