[RndTbl] Subdomain wildcard in Bind-style DNS editing

I have a question about subdomain wildcards in Bind-style DNS editing, so that I can more conveniently edit DNS zone files to implement Fastmail's support of MX records specifying "*.mydomain.com." for e-mail at subdomains. (Yes, Fastmail's documentation states their support for this.) Now, in Bind-style DNS, we have valid short notations for full FQDN in the name field (the left side) as follows: "@" = "mydomain.com." "abc" = "abc.mydomain.com." So my question is, might the following also be valid? "*" = "*.mydomain.com." "*.@" = "*.mydomain.com." Hartmut