How Basic Survey Linework Codes Work
Jeff Moris, a Senior Application Expert for IMAGINiT, steps through some Civil 3D Survey automatic Linework generation fundamentals for Linework Code Sets and their relationship to Figure Prefix Dbs.
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This truly is Linecode 101 - How to get a start in automatic linework generation in Civil 3D Survey from ground zero.
Jeff does skip the Survey and Survey Db Settings setup steps that are necessary to make this work to focus on the basics of automatic linework generation from a raw PNEZD text file.
It really isn't necessary to Reimport the data file each time. You can reprocess the Figures with new Linework Code Set and Figure Prefix Db settings with the Process Linework command.
The Survey Db data format is upgraded in Civil 3D 2020. Linework generation does still function the same.
Linecode Video Series
The Framework for Civil 3D includes 2000+ Codes, matched Description Keys, Figure Prefix Dbs, and all the above resources. This makes it a better place to start.