There is really nothing in the online manual about Budget Entry.
This is a new register in Hansa 8.5.
What is at http://www.hansamanuals.com/main/langcode___ET/mailnumber___3656/theconf___541/manuals/levelzero___3656/version___43/hwconvindex.htm is Entering Budgets and not the new Budget Entry Register.

Please check Module Nominal Ledger >> Register >> Budget Entry

There is a bug in that Budget Entry that it doesn't want to Save/Post and if you type something you cannot delete it.