Hi @amos c thank you for posting in the community! Just to confirm are you looking for the line options shown in the example image you've shared? 

Chen's Notation ERD shapes can be found in our UML Entity Relationship shape library (under the UML category in your Shapes Manager.) You can take a look at our Template Gallery to browse for templates using this shape library. 

I hope this helps! Please let me know if this is not what you are looking for or if you have any questions! :)

Yes I'm looking for the line options the one with an arc on the line itself. It's not found anywhere on LucidChart unless i'm missing something.

Hi @amos c thank you for clarifying that. Unfortunately the line options you are looking for are not currently supported in Lucidchart. If you have an image file of a line with an arc you could import that into Lucidchart and save it as a custom shape for easy access. 

If you would like to see Chen notation line options for extended ERD available in Lucidchart would you mind adding your idea to our Product Feedback space? Ideas submitted to this forum are passed on to the product development team for their consideration.

Thanks for your request and I apologize for any inconvenience this causes you. Please feel free to let us know if you have any additional questions about this!