Identifies which phase of a multi-phase task a progress message belongs to, so the client can label
the bar accordingly (e.g. zip import counts archive entries while "extracting", then notes while
"processing"). Single-phase tasks omit it and the client falls back to a generic message.
Identifies which phase of a multi-phase task a progress message belongs to, so the client can label the bar accordingly (e.g. zip import counts archive entries while "extracting", then notes while "processing"). Single-phase tasks omit it and the client falls back to a generic message.