versionlocal.xml in %TC_ROOT%\install dir contains following info. Here, QRMNumber is the patch number as far as I understand.
As @xplm2005 shown already
Major Version.Minor Version.QRM Number.Phase or IRM number
Major Version: They include major changes to the functionality of the product, enhancements, and usually involve changes to the database.
Minor Version: It designates a maintenance release that doesn't preserve data compatibility with the major enhancement release.
QRM Number: Quick Response Maintenance (QRM). QRMs are intended to release quick fixes to the field.
QRMs are usually reserved for fixes to the product although simple enhancements and minor functionality changes can find their way into them. QRMs preserve two-way data compatibility with all releases that share the same major/minor release.
IRM Number: In the context of a major release, this field identifies the phase number and is used to identify beta versions. In the context of a QRM release, this field identifies an Immediate Response Maintenance Release (IRM). If absolutely necessary, an IRM can be shipped to a customer to address a critical problem. IRMs preserve two-way data compatibility with all releases that share the same major/minor release.
Recommended System Configuration: