Restore Portfoilio plans from backup

[Thomas Humphries]

Hi - I want to be sure I can backup JIRA portfolio content, configuration etc with the JIRA backup function and restore it / import it?  It's not clear how to do this - the only article I found which discussed it is 4 years old and points to a dead link.  (https://community.atlassian.com/t5/Jira-Core-questions/Import-portfolio-backup/qaq-p/448307 )

There is nothing appearing in portfolio documentation search for "backup" or "restore" as a keyword. 

Can documentation be provided or reassurances on the procedure given please.