Base64Decode(Products::Base64;"question.png") returns 
when Products::Base64 is set to a string that begins with "iVBORw0KGgoAAAANSUhEUgAAAB8". The Base64 string in this example was shortened for readability.
Returns either container or text content from text encoded in Base64 format.
Base64Decode ( text {; fileNameWithExtension } )text - Base64 text to decode.
fileNameWithExtension - the filename and extension for the file created from the decoded Base64 text.
text, container
FileMaker Pro 13.0
To decode a Base64-encoded value and return the result in a text field (or a variable used as text data), for the data parameter, specify text that was in UTF-8 format and then Base64 encoded.
To decode a Base64-encoded value that represents binary data, return the result in a container field (or a variable used as container data) and specify the fileNameWithExtension parameter. If a filename and extension are not specified, this function returns text rather than container data.
Base64Decode(Products::Base64;"question.png") returns when Products::Base64 is set to a string that begins with "iVBORw0KGgoAAAANSUhEUgAAAB8". The Base64 string in this example was shortened for readability.