The documentation provided by EA shows us an example xml tuning file, with some of the attributes translated:
<U>=tunableTuple;
<T>=tunable;
<L>=TunableList;
<E>=TunableEnum;
c=class
n=name
i=instance type
m=module
s=instance id
ev=enum value

But where is the full list of attributes? I suspect the tdesc and tunable file directly correspond (more or less), but I am trying to put together an XML tuning file template for Trait, and there are attributes in the tdesc that I don't know what to do with.
I don't know the attribute code for these:

default
display
filter
group
resource_types
description
path
instance_substances_only
use_guid_for_reference
export_modes
static_entries
mapping_key
mapping_value
category
choice_query
choice_source
unique_entries
argument
restrict
dynamic_entries

Or for these:

<TunableVariant>
<Check>