Residencia Renewal Question

[Lynne]

I just put 'Permanently' on mine.

[alfie]

I know this may seem a stupid question, bit I'm in the process of completing my EX16 in order to re-new my residencia, and one of the questions asked is:
'Periodo previsto de residencia en Espana' -or, 'How long do I expect to be resident in Spain' Not knowing the precise date of my demise, am I able to simply state 'Para siempre' or do I actually have to put an estimated number of years ?
Many Thanks
Alfie