# BEL parser grammar issue in c#

**Category:** [Tools](https://discourse.openehr.org/c/tool-dev/36)
**Created:** 2023-07-03 15:50 UTC
**Views:** 460
**Replies:** 2
**URL:** https://discourse.openehr.org/t/bel-parser-grammar-issue-in-c/4177

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## Post #1 by @saeedsamie46

I am trying to use new BEL combined grammar in my developing tool. I could generate the parser and lexer files and it is working well for 'adl' and 'cadl' but when I want to use it for BEL parsing it gives me "NoViableAltException" error when parsing 'rawPath' rule. I could not find the source of ambiguity. I appreciate if you could give me a hint. I am using a c# project in VS 2019 and I used the ANTL4 tool 4.13 (the latest version) for generating the codes.

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## Post #2 by @saeedsamie46

Hi everybody. I finally found the problem and the solution. The problem was for undefined "Root_Id_Code" in AdlPathParser for the "idCode" rule. Adding this option to the rule solved the problem. Hope it helps others.

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## Post #3 by @Seref

Thanks for sharing the solution. A pull request fixing the problem would be even better, and openEHR repositories could always use a more collaborative look: the more people contributing the better, no matter what the contribution is.

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**Canonical:** https://discourse.openehr.org/t/bel-parser-grammar-issue-in-c/4177
**Original content:** https://discourse.openehr.org/t/bel-parser-grammar-issue-in-c/4177