As Rob1n said, the file needs to be in plain text. This is an example:

[Category: XXX]
[Card, Icon: 19]
Name: Whatever
User ID: my_name
Password: Cleartext
Note:

[Card, Icon: 19]
System: VPN
Login: my_login
Password: Cleartext
Access:
Other:
Note:

Here we have one category ("XXX"), which contains one item ("Whatever") with 2 details ("User ID" and "Password"). And have one item ("VPN") with 2 details ("Login" and "Password"), that are not inside the category "XXX".

If it is not correct, I'm sorry! I don't have anymore a Symbian device, and I don't use Windows in my computer, so I cannot use Handy Safe and try to understand the format of the file that it creates.

If somebody send me an example file, with several lines, categories and details, I could try to write the import code.