The following parameters may help more precisely locate your research results:
1. “+” means “and”. If you put this mark between two words, it means that these two keywords must occur concurrently in your search results. E.g., “legal + system” means that these two words must exist concurrently in your search result, but it does not necessarily, though could, mean that the result will be “legal system”.
2. “and”: same as above.
3. “&”: same as above.
4. “|”: means “or”. If you put this mark between two words, it means that either of the two keywords must occur in your search results. E.g., “legal/system” means that at least one of these two words must exist in your search result, but it does not necessarily, though could, mean that only the document can include only one keyword. They may occur at the same time.
5. “or”: same as above.
6. “ ”: If you put your keywords within quotation marks, it means that you wish to search the database with the keywords arranged exactly in the right sequential order. E.g. “commissioned customs declarations” means you wish so search the database with all these keywords and appear in the word order as shown in the quotation marks.