Thx edison, I looked at your reference, and have snipped it out for review by others. Somebody is confused: me, the cisco tech writers or the cisco dev guys; the TIP below mentions this is a useful command for saving the config without having to go back into EXEC mode (exactly what i want to do), but then a few lines later, it says you cannot use it with the "copy" or "write" command in global config mode.
anyway, i decided to test: "do copy run star", which does work. I just need to train myself to use this command from config mode - instead of "copy wr mem" - until cisco clears up their confusion and removes this feature - please dont!
makes me feel good knowing cisco is probably confused as well. cisco dev guys => change the feature back to the way it was before, please!
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Usage Guidelines
Use this command to execute user EXEC or privileged EXEC commands (such as show, clear, and debug commands) while configuring your routing device. After the EXEC command is executed, the system will return to the configuration mode you were using.
Tip 
This command can be useful for saving your configuration to the startup-config file without having to return to the user EXEC mode or privileged EXEC mode (do copy running-config startup-config) or for checking the status of a feature (using a do show command) while configuring the feature.
Caution Do not enter the do command in user EXEC mode or privileged EXEC mode. Interruption of service might occur.
You cannot use the do command to execute the configure terminal command because entering the configure terminal command changes the user EXEC mode or privileged EXEC mode to the global configuration mode.
You cannot use the do command to execute copy or write commands in the global configuration or any other configuration mode or submode.
