Tip #49 Command Line Syntax and Quotations in Embase on Ovid

The Crux: when including the terms use, root, scope, or ptx (a protein) in a search query, you may need to apply quotation marks either around the term or around the phrase in which it appears.

Many databases ignore or remove frequently occurring terms from search queries to expedite processing time. So called stopwords in Embase are and, as, for, from, is, of, that, the, this, to, was, and were.

The stopword and is also a Boolean operator. If you use and in an advanced search, it will not be ignored but will act as an operator unless you enclose it in quotation marks, which will render it a stopword. Either way, your search should not result in a database error or baffling results.

A notable exception in Embase (Ovid) are controlled vocabularies. A search for aerosolized particles and droplets/ [forward slash signifies a subject heading], will return zero results. However, if you enclose it in quotation marks, "aerosolized particles and droplets"/, you'll correctly retrieve 146 records. The reason is that without quotes, and acts as an operator. With quotes, it's operator function is silenced so that the precise subject heading can be retrieved from this phrase indexed field. Surprisingly, you can enclose only the word use in quotes and it works - in other words aerosolized particles "and" droplets/ also returns 146 records.

There are other terms that are neither stopwords nor operators but act on their own or on adjacent terms and must also be enclosed in quotations in some instances in Embase's advanced search. Failure to do so will result in a database error. These are known as command terms and are part of Embase's advanced search command line syntax. Embase offers functionality for two types of command line syntax inaptly and inconsistently named command syntax (also known as dot-dot commands) and sentence syntax. I am addressing sentence syntax. This post applies only to Advanced Search mode.

Link to Embase field guide

The command terms use, root, scope, and ptx perform the following functions, which are detailed in the database field guide.

• Use switches your current search session to a different database.
• Root opens the designated field index, displaying at the position of the search term indicated.
• Scope opens the scope note display of the search term indicated.
• PTX opens the permuted index display for the subject heading indicated.

If you are utilizing a command term for its intended purpose, quotes would not be used. However, if you are employing use, root, scope, or ptx (a protein) as a search term, you will will enclose them in quotation marks in some instances.

Let's unpack this.

The Use Command in Advanced Search

The search drug use.ti returns an error.

 

A search for "drug use".ti returns 13,940 records

The search drug "use".ti converts to "drug use".ti. and returns 13,940 records. Ovid Help states that you must use quotes around the entire phrase or it will result in a syntax error message, however, enclosing use only worked.

Searching drug-use.ti returns 13,940, confirming that a hyphen between terms works the same as quotation marks around the phrase.

A search using the radio button Title for the article Association between cannabis use and brain imaging phenotypes in UK Biobank: An observational and Mendelian randomization study results in a database error because it contains the term use. An easy fix is to enclose either use or the entire title in quotation marks.

Drug use without quotes causes an error in Search Tools/Map term, which is how I look for subject headings, whereas, "drug use" and drug-use map to the subject heading "drug use."  

It would follow that drug use/ in an advanced search query would also cause an error and it does. The correct way to enter drug use as a subject heading in a query is "drug use"/ 

Search Fields, Embase's tool for searching individual indexes, also requires quotation marks around "drug use." A search in the heading word (hw) field for "drug use" results in 151,201 records that would not be returned if quotes weren't applied.

Of note: a search for "use"/ retrieves 2 records, even though use is not a subject heading. A look at one of the records shows that use is in candidacy for designation as a subject heading but not yet a subject heading. It bears repeating that the query use/ would result in an error without quotation marks.

Candidate term use in an Embase record

 

 

All other options under Search Tools, such as Thesaurus, Permuted Index, Scope Note, Explode, and Subheadings allow a search for drug use without quotation marks.

Commands Root, Scope, and PTX in Advanced Search

Command terms root, scope, and ptx operate differently from use in a fundamental way - they can be used singularly or with a term preceding; but if used preceding another term they will act on that term. Exceptions would be preceding operators and, or, not, etc. For example:

The query root.ti results in 60k records

The query plant root.ti results in 300 records

The query root hair.ti commands the database to to display the title field index for the word hair; whereas "root hair".ti, "root" hair.ti, and root-hair.ti return 500 results.

The query root hair/ causes an error; while "root hair"/ returns 700 results.

The query root/ (root is not a subject heading) still results in 43 records, another instance of candidate terms at play. Remember you won't find candidate terms in the thesaurus as they are in candidacy and not yet subject headings.

Limited testing reveals that commands scope and ptx operate similarly to root. If you discover an exception or additional terms requiring quotations, please let me know!

That's all I've got!