[#BloombergLP-bsls-TimeInterval-operator_plus_eq-058] = xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bsls.adoc[bsls]::xref:BloombergLP/bsls/TimeInterval.adoc[TimeInterval]::operator+= :relfileprefix: ../../../ :mrdocs: Add to this time interval the value of the specified `rhs` time interval, and return a reference providing modifiable access to this object. The behavior is undefined unless the total number of seconds in the resulting time interval can be represented with a 64‐bit signed integer. == Synopsis Declared in `<bsls_timeinterval.h>` [source,cpp,subs="verbatim,replacements,macros,-callouts"] ---- xref:BloombergLP/bsls/TimeInterval.adoc[TimeInterval]& operator+=(xref:BloombergLP/bsls/TimeInterval.adoc[TimeInterval] const& rhs); ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#