5.6 Simultaneous Access to Multiple Records

Selection functions that accept record arguments (annopen, isigopen, osigopen, and wfdbinit) normally close any active database files of the types with which each deals before proceeding. The argument +record is synonymous with record, but has the effect of causing these functions to leave any active files open. (For convenience, the other functions that accept record arguments — sampfreq, newheader, and setheader — also treat record and +record as synonymous, but without any noticeable effect.) The restrictions on the total numbers of signals and annotation files still apply.

If the sampling frequencies or lengths of the records do not match, a warning message will be produced (unless wfdbquiet was invoked). The time-conversion functions (see section timstr and strtim) will continue to use the sampling frequency and base time defined for the first record that was opened, unless these attributes are reset by sampfreq, setsampfreq, or setbasetime.

Function calopen uses the ‘+’ convention for calibration file names. Although it normally creates the calibration list from scratch each time it is called, it retains the current calibration list if the calibration file name is prefixed by ‘+’.