asset search - keywords and the expected values:

type: item type names
group: group name (battleship,mineral,fighter bomber)
category: category name (ship,module,commodity)
minimum: stack size
maximum: stack size
metalevel: metalevel
metagroup: meta group name (faction,storyline,officer)
techlevel: tech level (1,2,or3)
minsecurity: solar system sec level (-1.0 - 1.0)
maxsecurity: solar system sec level (-1.0 - 1.0)
security: security as text (high,empire,low,null,zero)
system: solar system name
constellation: constellation name
region: region name
station: parts of station names
blueprint: copy or original

Text must be enclosed in double quotes if more than one word. If not only the first word will be used and the rest is lost into the ether.
group:fighter bomber -should be- group:"fighter bomber"