[mythtv-users] what's the definition and usage of channel number, freqid, callsign and name of mythconverg.channel

[Clark Lee]

Hi, All,

I am trying to setup channel information for Beijing's local digital cable broadcast for mythtv.
The digital cable company provide a free STB that can be controlled by a remote. I managed to use LIRC and external script to control it, switch the channel by sending digital channel number. One digital channel number is corresponding to one specific channel. E.g. "1" is for "China Central Television Station - 1".

Because there is no XMLTV data available, I am editing the 'channel' table in mythconverg database manually.
However, I am a bit confused about the following columns and what I should fill in for digital cable case.

channum;
=> no idea 
freqid;
=> from my past experience it is used in Analog TV case where it is used to control the tuner.
callsign;
=> no idea...
name;
=> This seems should be the real name (i.e. man readable names) of the channel.

Which one is used as the input parameter for "external channel changer"? 
What exactly are these columns for?  

I am using recent 0.22 trunk 21727. 

Thanks very much,

Clark