Some Cluster B3 and B4 phages have an intein in the middle of their terminase gene. To learn about inteins see this paper:
Kelley DS, Lennon CW; SEA-PHAGES; Belfort M, Novikova O. Mycobacteriophages as Incubators for Intein Dissemination and Evolution. mBio. 2016 Oct 4;7(5):e01537-16. doi: 10.1128/mBio.01537-16. PMID: 27703073; PMCID: PMC5050341.

To visualize an example of terminase with or without an intein, create a phamerator map with phage Kronus and Casbah (both B3). Note that presence of an intern may lead to identical proteins being assigned to different phams.