1) The label - and hence the letters - are for an exporter, not for Toso or some other maker. See the thread I linked to.
2) Although I agree that those type of canes may be linked to Toso, we should always bear in mind that on Murano lots of makers used canes from a few sources. So they may be Toso canes used by anoher maker. However, as stated in the thread I linked to, the exporter dealt mainly in Toso, therefore it's likely, but not yet proven, that these are Toso items.