| Attribute Type | Expanded Form | Count |
| TERMUI | Term unique identifier | 971850 |
| TH | MeSH Thesaurus ID - identifies thesauri other than MeSH in which the MeSH heading or cross-reference is included. | 887601 |
| HM | MeSH Heading Mapped To - heading mapped to attribute in C-MeSH containing repeating (MH or MH/SH) elements (e.g. HM = PYRROLIDINONES, HM = *TARTRATES, HM = ESTRONE/* analogs & derivatives) | 429517 |
| RN | Registry Number - series of numbers and hyphens (any leading zeros in an RN are dropped) or a series of numbers and periods, preceded by EC | 379057 |
| MDA | MeSH date of entry YYYYMMDD - date the term was added to the MeSH file, which is prior to the date the term became available for indexing and searching MEDLARS citations. Terms that have been part of MeSH for many years may have no value in this element. | 349516 |
| SC | MeSH Supplemental record class. | 318986 |
| FR | MeSH Frequency | 318925 |
| MMR | MeSH revision date YYYYMMDD - date of the last major revision to the term's MeSH record. | 276670 |
| SRC | MeSH Literature source of chemical name - a citation to an article in a journal indexed for MEDLINE in which the chemical has been identified. (Note: Not to be confused with source abbreviation of SRC) | 251949 |
| SOS | Scope Statement | 215226 |
| MN | MeSH hierarchical number for the concept in the MeSH tree structures. This number also appears in the HCD subelement of the REL and CXT elements. | 63145 |
| PI | MeSH heading or heading/subheading combination(s) followed by a date range in parentheses (YYYY). | 54960 |
| II | MeSH Indexing Information - for MeSH chemical terms (Term Type=NM), MeSH headings that may be relevant to articles that are also assigned the NM term. | 46470 |
| RR | The Chemical Abstracts Registry numbers for salts, optical isomers, or isotope-labeled versions of the concept followed by the relationship of this RR to the RN (in parentheses.) Applies to chemicals only. These numbers can be used as links to information in a number of chemical and toxicological databases. | 43452 |
| DC | MeSH Descriptor class - type of MeSH term the concept name represents. | 30454 |
| DX | MeSH Date major descriptor established YYYYMMDD - first day of the Index Medicus publication month in which the descriptor (in any form) was available for searching as a major descriptor. | 30454 |
| AQL | MeSH Allowable Qualifier - list of allowable qualifier abbreviations for MeSH main headings (e.g. AA, CL, CS, DF, DU, IM, I,P ME, PK) | 29219 |
| HN | History Note - for MeSH history notes, the year when the current form of the MeSH term was established as a major and/or minor descriptor. | 26518 |
| PM | Public MeSH note - combines key information from the HN and PI elements in a format that is printed in the MeSH publications. | 26003 |
| LT | Indicates if a chemicals or medical device is a tradename (present in older versions of the Metathesaurus and was discontinued, then brought back starting in 2002AD) | 15926 |
| PA | Pharmacologic Action of MeSH main headings (MH) for drugs and supplementary concept names (NM). The information in this element is also represented by an "isa" relationship between the MH or NM concept and the MeSH concept name for the class of drugs with a particular pharmacologic action. | 15028 |
| AN | MeSH Annotation - an informative MeSH note written primarily for indexers or catalogers that may also be useful in explaining the use of a MeSH term to online searchers. | 12598 |
| FX | MeSH MH Mapping - maps a MeSH MH to a 'See Related' MH. | 9106 |
| OL | MeSH Online Note - information helpful to online searchers of MEDLINE, especially when the history of a term or cross-reference has implications for online searching. This is a potential source of useful information for rules for search interface programs. | 3038 |
| EC | Specifies the MeSH main heading to be used instead of the Descriptor/Qualifier combination specified in the EC_OF attribute. | 985 |
| DQ | MeSH Date Qualifier Established YYYYMMDD - date the qualifier became available for indexing MEDLARS citations. | 76 |
| CX | MeSH Consider Also Note - other word roots or prefixes that should be consulted for concepts related to this MeSH concept, e.g., the value for "Heart" is "consider also terms at cardi- and myocardi-". | 66 |
| Relation Name/Additional Label | Expanded Form | Count |
| QB/ | can be qualified by./Empty relationship attribute | 621252 |
| AQ/ | Allowed qualifier/Empty relationship attribute | 621252 |
| RN/mapped_to | has a narrower relationship/Mapped to | 429517 |
| RB/mapped_from | has a broader relationship/Mapped from | 429517 |
| SY/has_permuted_term | source asserted synonymy./Has permuted term | 129276 |
| SY/permuted_term_of | source asserted synonymy./Permuted term of | 129276 |
| RB/ | has a broader relationship/Empty relationship attribute | 99484 |
| RN/ | has a narrower relationship/Empty relationship attribute | 99484 |
| PAR/ | has parent relationship in a Metathesaurus source vocabulary /Empty relationship attribute | 41715 |
| CHD/ | has child relationship in a Metathesaurus source vocabulary /Empty relationship attribute | 41715 |
| RO/mapping_qualifier_of | has relationship other than synonymous, narrower, or broader/Mapping qualifier of | 35186 |
| RO/has_mapping_qualifier | has relationship other than synonymous, narrower, or broader/Has mapping qualifier | 35186 |
| RO/ | has relationship other than synonymous, narrower, or broader/Empty relationship attribute | 29290 |
| SY/has_entry_version | source asserted synonymy./Has entry version | 16163 |
| SY/entry_version_of | source asserted synonymy./Entry version of | 16163 |
| RB/inverse_isa | has a broader relationship/Inverse is a | 15028 |
| RN/isa | has a narrower relationship/Is a | 15028 |
| SY/sort_version_of | source asserted synonymy./Sort version of | 3926 |
| SY/has_sort_version | source asserted synonymy./Has sort version | 3926 |
| SY/has_expanded_form | source asserted synonymy./Has expanded form | 78 |
| SY/expanded_form_of | source asserted synonymy./Expanded form of | 78 |
