As detailed in clause 3.4 of the Licence, there are certain extent limits beyond which copying should not exceed. This remains the case in the DCS, and the system alerts you if it appears that a breach of extent limits is likely. Remember that extent limits apply to a Course of Study, so that if different material from the same source is required for a different Course of Study, this is fine.
The DCS will search OCLC and your integrated LMS (if you have this set up) to find the total number of pages of the work you are copying from. It will then work out the percentage of the work you are copying, and notify you if this is within the extent limits.
If this cannot be found, you can enter this manually:
If the DCS works out that the extract is more than 10% of the source, you can confirm that it is 1 chapter.