# Basic DCG example predicates

**URL:** <https://swi-prolog.discourse.group/t/basic-dcg-example-predicates/2638>\
**Category:** Nice to know\
**Created:** [July 15, 2020, 3:54pm UTC](https://swi-prolog.discourse.group/t/basic-dcg-example-predicates/2638 "2020-07-15T15:54:06Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\
**Post date:** [July 16, 2020, 1:11pm UTC](https://swi-prolog.discourse.group/t/basic-dcg-example-predicates/2638/3 "2020-07-16T13:11:44Z")

</div>

The overall syntax is like this. The block’s first line must start with `%!`

```prolog
%! <mode declaration>
% Markdown
% @key nodes

```

You can simply see what do did using this command line. That should open a browser on the file’s overview page.

```
swipl --pldoc myfile.pl
```

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_[View the full topic](https://swi-prolog.discourse.group/t/basic-dcg-example-predicates/2638)._