Handling pre-parsed XLSX file

Specific Domains Data
2

I think you just need to base64decode everything that follows base64,:

julia> using Base64

julia> String(base64decode("UEsDBBQABgAIAAAAIQBi7p1o"))
"PK\x03\x04\x14\0\x06\0\b\0\0\0!\0b\xee\x9dh"