Tweaking of Combining involved people action

Hi All,
i currently use the following action to combine the technical roles to the involved people field. it works well except for one aspect. it currently formats the field as follows if there are multiple people in one field: producer:person; producer:person; mixer:person; mixer:person etc. What part of the action do i need to alter for it to format as follows: producer:person one, peron two; mixer:person one, person two; etc.
Any help would be greatly appreciated.

[#0]
T=4
F=PRODUCER
1=^(.+)
2=producer:$1;
3=0

[#1]
T=4
F=LYRICIST
1=^(.+)
2=lyricist:$1;
3=0

[#2]
T=4
F=ARRANGER
1=^(.+)
2=arranger:$1;
3=0

[#3]
T=4
F=ENGINEER
1=^(.+)
2=engineer:$1;
3=0

[#4]
T=4
F=WRITER
1=^(.+)
2=writer:$1;
3=0

[#5]
T=4
F=MIXER
1=^(.+)
2=mixer:$1;
3=0

[#6]
T=5
1=$regexp($meta_sep(involvedpeople,;);$meta_sep(arranger,;)$meta_sep(producer,;)$meta_sep(engineer,;)$meta_sep(mixer,;)$meta_sep(lyricist,;)$meta_sep(writer,;),(;;)+,;)
F=INVOLVEDPEOPLE

[#7]
T=4
F=INVOLVEDPEOPLE
1=^;
2=
3=0

[#8]
T=9
F=ARRANGER; PRODUCER; MIXER; ENGINEER; WRITER;LYRICIST

Please let us know what kind of Actions do you use.
T=4 stands for?
T=5 stands for?
T=9 stands for?
What is the meaning of 3=0 and 2=?

I would add the label string (e.g. Mixer) not in the field MIXER but only when you add the various names to INVOLVEDPEOPLE to that it looks like
Arranger: $meta_sep(arranger,;); Producer: $meta_sep(producer,;)$meta_sep(...