IBM MeAns Service Button with 13 stripe logo - a true ThirteenStriper  
Closeup the IBM thirteen stripe logo - Yes a true Thirteenstriper !
The 13 stripe logo first appeared on the masthead of at least one System 360/TSS and documents related to virtual memory and the time share operating system that became the heart of the System 370.
It was quickly replaced by the official eight strip logo due to its poor overall contrast. For this and other printing concerns IBM continued to use the pointy M block letter logo until the early 70's when use of the official eight stripe logo became mandated.

Closeup the IBM thirteen stripe logo - Yes a true Thirteenstriper !
The 13 stripe logo first appeared on the masthead of at least one System 360/TSS and documents related to virtual memory and the time share operating system that became the heart of the System 370.
It was quickly replaced by the official eight strip logo due to its poor overall contrast. For this and other printing concerns IBM continued to use the pointy M block letter logo until the early 70's when use of the official eight stripe logo became mandated.