what is this code?

hi...when i load some course in the menu item, some of course has some link such as this:
mywebsite.com/index.php?option=com_joomd...e_id=24:3&Itemid=275
and you can see >> &course_id=24:3 << what is 3?
i see in the source , and that's variable name is $course_slug.
courses that has this variable in that's link, not loaded correctly and the course detail page is empty.
my question:
1-what is $course_slug and when use?
2-i remove that and my link correctly work.is my work harmful for other side of joomdle?

Hi,

Course slug is the URL-friendly conversion of the course name... so I am not sure why you would get a "3" there, or why it fails.
If you want, email me instructions on how to see the problem live.

my website is in the non-english language and maybe not known for you.but i send as soon as possible to your mail.
tnx

i find new information
it seems $course_slug can't show non-english character...and in this case i have some number in my course title .
to clarify:
1- if i have a course with title for example "تست" it is not render at all in the $course_slug
2- if i have a course with title for example "2تست" then the $course_slug = 2
3- if i have a course with title for example "test" then the $course_slug = test
4- if i have a course with title for example "test2" then the $course_slug = test2

i send the demo of the problem in email.