The wcag.portfolio_metadata=x can be used to set the metadata field that accessibility auditor uses to determine the portfolio labels.
If you have an existing metadata field with the unique labels then you can set the value to this.
Normally you assign profiles by creating an external metadata field that maps the URLs to the portfolio names, using the preset x metadata field
Would assign pages from health.gov.au and tga.gov.au to a portfolio named 'Health' and pages from environment.gov.au to a portfolio named 'Environment'.
Note: after making changes to the external metadata file you will need to do a full update (advanced update: full update) to make sure all pages are recrawled and processed for WCAG. Also, changes will only apply for future reports, historical data will remain labelled as unknown.
See: https://docs.funnelback.com/15.8/more/extra/accessibility_auditor_collection_administration.html#portfolio-specification for more information.
Note: this only applied for accessibility auditor reports in Funnelback 15.8 and earlier. The accessibility auditor was rewritten for 15.10 and portfolios no longer exist.