I was running it to see if it had newer style cathodes as compared to the Mazda ones. Well, inbetween. The aging marks look similar to the 60's GE lamps.
I have 3 more that say Std. Cool White so I assume they are newer. I came home to the desk lamp flashing. The end blackening was short as in those with the short electrodes. I do not know if it has the metal "bar" parallel to the electrodes as the Mazda lamps do. It will burn in my trigger start fixture, but not very happily. 

Any idea of when improvements and changes were made and then stopped ?  The current GE 15 watt T8 lamps made in Indonesia tend to make around 5000 hours AT BEST.