It's likely that the term "Tabuko" refers to a specific location or ethnic group, and you may be referring to the indigenous people of that area.
Here's why it's difficult to determine a specific alphabet:
* Pre-colonial Philippines had diverse scripts: The Philippines was home to various indigenous groups with their own languages and writing systems. These systems were primarily syllabic or logographic, rather than alphabetic.
* Limited documentation: Most of the pre-colonial scripts have not survived due to the destruction of materials by the Spanish.
* Variations in terminology: The term "Tabuko" might not be a common or recognized historical designation.
To help identify the possible scripts used, it would be helpful to know:
* What specific location or ethnic group are you referring to?
* What time period are you interested in?
Here are some of the known pre-colonial scripts in the Philippines:
* Baybayin: This script was used by the Tagalog people and is the most studied and documented pre-colonial script.
* Hanunó'o: This script was used by the Hanunó'o people of Mindoro.
* Buhid: This script was used by the Buhid people of Mindoro.
* Tagbanwa: This script was used by the Tagbanwa people of Palawan.
Further research on the specific location or ethnic group you're interested in might reveal more information about their writing systems.