Notification Vs transaction type

Dear friend ,

I am working with Sol Man 4.0 Sp 13.

I am configuring for support desk in Sol Man (SLFN / SLF1)

In support desk config, i am getting two terminologies..namely

1. Basis notification

2. Transaction type (SLFN / SFL1)

What is the importance of notification whlie configuring support desk

How Notification is being linked with transaction type (SLFN / SLF1)

Without notification can we create support desk message?

Or can i manually create notification only?

Regadrs

Senthil