Query key. This integer specifies which of the UID lists attached to the given Web Environment will be used as input to EFetch. Query keys are obtained from the output of previous ESearch, EPost or

ELInk calls. The query_key parameter must be used in conjunction with WebEnv.

WebEnv

Web Environment. This parameter specifies the Web Environment that contains the UID list to be provided as input to EFetch. Usually this WebEnv value is obtained from the output of a previous ESearch, EPost or ELink call. The WebEnv parameter must be used in conjunction with query_key. efetch.fcgi?db=protein&query_key=&WebEnv=

Optional Parameters – Retrieval

retmode

Retrieval mode. This parameter specifies the data format of the records returned, such as plain text, HMTL or XML. See for a full list of allowed values for each database.

Table 1 – Valid values of &retmode and &rettype for EFetch (null = empty string)

rettype

Retrieval type. This parameter specifies the record view returned, such as Abstract or MEDLINE from PubMed, or GenPept or FASTA from protein. Please see for a full list of allowed values for each database.

retstart

Sequential index of the first record to be retrieved (default=0, corresponding to the first record of the entire set). This parameter can be used in conjunction with retmax to download an arbitrary subset of records from the input set.

retmax