FM10 index maker text

Hi.

In the FM10 manual, it says the text of the index entry in the Marker panel can be entered up to 255 characters (127 Japanese double-byte characters).

But, When I entered 500 English characters or 300 Japanese characters, the index marker can be generated and no message to tell me the marker

text is too long.

In the FM7, if I entered more than 256 character or 128 Japanese characters, FM7 shows the message that marker text is too long.

How many characters in the marker text limited in FM10?

Regards

erieru103