Thanks, sorry my English was not clear, the Datatype Targa (the one found on Aros Archive) works very well, but it works only if you use the "Pattern=?.tga", but in this way the TGA files without extension will not be recognized.
I was looking for the parameter to add on "Mask=" in this way even files without extension would be recognized.
For all other Formats I have created the Descriptor with the right parameter in "Mask=", i just need the TGA