/sys$common/syshlp/helplib.hlb READ, Qualifiers, /KEY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /KEY=string

    Reads a record with the key that matches the specified character
    string. Binary and integer keys are not allowed. This qualifier,
    when used together with the /INDEX qualifier, allows you random
    access to indexed files.

    Key matches are made by comparing the characters in the /KEY
    string to characters in the record key.

    To read records at random in an indexed file, you must specify
    the /KEY qualifier. Once a record is read randomly, all
    subsequent reads without the /KEY qualifier access records in
    the indexed file sequentially.