4.11.3.5 Arch
   
The Arch build step performs an Arch checkout or update using the tla client. It takes the
following arguments:
     
url- (required): this specifies the URL at which the Arch source archive is
available.
     
 version- (required): this specifies which “development line” (like a branch)
should be used. This provides the default branch name, but individual
builds may specify a different one.
     
 archive- (optional): Each repository knows its own archive name. If this
parameter is provided, it must match the repository's archive name. 
The parameter is accepted for compatibility with the 
Bazaar
step, below.