Display Option is as above . Maximum Articles indicates how many articles you wish to have displayed at a time, with the most recent entries being displayed first. This argument is used to help NCBI provide better service to third parties generating Entrez queries from programs. As with any query system, it is sometimes possible to ask the same question different ways, with different effects on performance. NCBI requests that developers sending batch requests include the 'Tool' argument.
Searches using terms and fields can return a lot of documents.
Tool Expression is created from one or more terms , separated by operators . Notes Boolean Expressions are normally processed left to right. If you wish part of your boolean expression to be processed out of order, enclose it in parentheses. This argument is used to help NCBI provide better service to third parties generating Entrez queries from programs. As with any query system, it is sometimes possible to ask the same question different ways, with different effects on performance.