The available commands

command -option <value> ... <sourcevalue>

In this mode the command processes the given <sourcevalue> and returns the transformed information as interpreter result. With tcl 7.6 this may yield incorrect results due to embedded \0 characters, either in source or result.

To allow for correct operation with this version too 2 additional options are provided: -in and -out.

If option -in is present, its argument is interpreted as channelhandle and the data to transform is read from it. A <sourcevalue> must not be specified in that case.

If option -out is present, its argument is interpreted as channelhandle and the transformation result will be written into it.

Please note that it is not necessary to specify both options, each of them can be used alone.

This mode is the one which required the patches to the older cores. Not so since version 8.2 of tcl. Without them we would be unable to stack our transforming channel onto the named one.

command -attach <channel> -option <value> ...

This creates a channel filter, configured as defined by the options and then attached to the <channel>. All data read from or written into the <channel> will be transformed accordingly from now on.

Neither -in nor -out nor a <sourcevalue> must be specified here.