diff --git a/roadmap.md b/roadmap.md
index 727e87a..2a7acfe 100644
--- a/roadmap.md
+++ b/roadmap.md
@@ -35,6 +35,7 @@
     - Maybe a partial markdown preprocess to support bold and italic?
 - Look into gr_curve to possibly add beziers to the kicad conversion
     - Support curves (arcs as well as Béziers) in polygons
+    - Also, three point arcs, tangents, earier "circle tools" in general
 - Add snappable line footprint
 - Figure out a manual, but still reasonably comfortable routing method directly from the config
 - Eeschema support for pcbs
diff --git a/src/assert.js b/src/assert.js
index 916fa81..ad55436 100644
--- a/src/assert.js
+++ b/src/assert.js
@@ -67,3 +67,14 @@ exports.trbl = (raw, name, _default=0) => units => {
     if (raw.length == 2) raw = [raw[1], raw[0], raw[1], raw[0]]
     return arr(raw, name, 4, 'number', _default)(units)
 }
+
+exports.asym = (raw, name) => {
+    // allow different aliases
+    source_aliases = ['source', 'origin', 'base', 'primary', 'left']
+    clone_aliases = ['clone', 'image', 'derived', 'secondary', 'right']
+    _in(raw, name, ['both'].concat(source_aliases, clone_aliases))
+    // return aliases to canonical names
+    if (source_aliases.includes(raw)) return 'source'
+    if (clone_aliases.includes(raw)) return 'clone'
+    return raw
+}
diff --git a/src/filter.js b/src/filter.js
index cbece43..ba7f5e7 100644
--- a/src/filter.js
+++ b/src/filter.js
@@ -108,7 +108,7 @@ const contains_object = (val) => {
     return false
 }
 
-exports.parse = (config, name, points={}, units={}, include_mirrors=false) => {
+exports.parse = (config, name, points={}, units={}, asym='source') => {
     
     let result = []
 
@@ -118,18 +118,23 @@ exports.parse = (config, name, points={}, units={}, include_mirrors=false) => {
 
     // if a filter decl is an object, or an array that contains an object at any depth, it is an anchor
     } else if (contains_object(config)) {
-        result.push(anchor(config, name, points)(units))
-        if (include_mirrors) {
+        if (['source', 'both'].includes(asym)) {
+            result.push(anchor(config, name, points)(units))
+        }
+        if (['clone', 'both'].includes(asym)) {
             // this is strict: if the ref of the anchor doesn't have a mirror pair, it will error out
             result.push(anchor(config, name, points, undefined, true)(units))
         }
         
-    // otherwise, it is treated as a condition to filter all available points
+        // otherwise, it is treated as a condition to filter all available points
     } else {
-        result = Object.values(points).filter(complex(config, name, units))
-        if (include_mirrors) {
+        source = Object.values(points).filter(complex(config, name, units))
+        if (['source', 'both'].includes(asym)) {
+            result = result.concat(source)
+        }
+        if (['source', 'both'].includes(asym)) {
             // this is permissive: we only include mirrored versions if they exist, and don't fuss if they don't
-            result = result.concat(result.map(p => points[anchor_lib.mirror(p.meta.name)]).filter(p => !!p))
+            result = result.concat(source.map(p => points[anchor_lib.mirror(p.meta.name)]).filter(p => !!p))
         }
     }
 
diff --git a/src/outlines.js b/src/outlines.js
index 8afcd9b..fe08c04 100644
--- a/src/outlines.js
+++ b/src/outlines.js
@@ -191,12 +191,12 @@ exports.parse = (config = {}, points = {}, units = {}) => {
             const operation = u[a.in(part.operation || 'add', `${name}.operation`, ['add', 'subtract', 'intersect', 'stack'])]
             const what = a.in(part.what || 'outline', `${name}.what`, ['rectangle', 'circle', 'polygon', 'outline'])
             const bound = !!part.bound
-            const mirror = a.sane(part.mirror || false, `${name}.mirror`, 'boolean')()
+            const asym = a.asym(part.asym || 'source', `${name}.asym`)
 
             // `where` is delayed until we have all, potentially what-dependent units
             // default where is [0, 0], as per filter parsing
             const original_where = part.where // need to save, so the delete's don't get rid of it below
-            const where = units => filter(original_where, `${name}.where`, points, units, mirror)
+            const where = units => filter(original_where, `${name}.where`, points, units, asym)
             
             const adjust = anchor(part.adjust || {}, `${name}.adjust`, points)(units)
             const fillet = a.sane(part.fillet || 0, `${name}.fillet`, 'number')(units)
@@ -209,7 +209,7 @@ exports.parse = (config = {}, points = {}, units = {}) => {
             delete part.operation
             delete part.what
             delete part.bound
-            delete part.mirror
+            delete part.asym
             delete part.where
             delete part.adjust
             delete part.fillet
diff --git a/src/pcbs.js b/src/pcbs.js
index bf07401..bb49ce6 100644
--- a/src/pcbs.js
+++ b/src/pcbs.js
@@ -281,9 +281,9 @@ exports.parse = (config, points, outlines, units) => {
         for (const [f_name, f] of Object.entries(footprints_config)) {
             const name = `pcbs.${pcb_name}.footprints.${f_name}`
             a.sane(f, name, 'object')()
-            const mirror = a.sane(f.mirror || false, `${name}.mirror`, 'boolean')()
-            const where = filter(f.where, `${name}.where`, points, units, mirror)
-            delete f.mirror
+            const asym = a.asym(f.asym || 'source', `${name}.asym`)
+            const where = filter(f.where, `${name}.where`, points, units, asym)
+            delete f.asym
             delete f.where
             for (const w of where) {
                 footprints.push(footprint_factory(f, name, w))
diff --git a/src/points.js b/src/points.js
index 2fd72f7..10ba6ed 100644
--- a/src/points.js
+++ b/src/points.js
@@ -128,7 +128,7 @@ const render_zone = exports._render_zone = (zone_name, zone, anchor, global_key,
             key.height = a.sane(key.height, `${key.name}.height`, 'number')(units)
             key.padding = a.sane(key.padding, `${key.name}.padding`, 'number')(units)
             key.skip = a.sane(key.skip, `${key.name}.skip`, 'boolean')()
-            key.asym = a.in(key.asym, `${key.name}.asym`, ['left', 'right', 'both'])
+            key.asym = a.asym(key.asym, `${key.name}.asym`)
 
             // templating support
             for (const [k, v] of Object.entries(key)) {
@@ -256,14 +256,14 @@ const parse_axis = exports._parse_axis = (config, name, points, units) => {
 const perform_mirror = exports._perform_mirror = (point, axis) => {
     if (axis !== undefined) {
         point.meta.mirrored = false
-        if (point.meta.asym == 'left') return ['', null]
+        if (point.meta.asym == 'source') return ['', null]
         const mp = point.clone().mirror(axis)
         const mirrored_name = `mirror_${point.meta.name}`
         mp.meta = prep.extend(mp.meta, mp.meta.mirror || {})
         mp.meta.name = mirrored_name
         mp.meta.colrow = `mirror_${mp.meta.colrow}`
         mp.meta.mirrored = true
-        if (point.meta.asym == 'right') {
+        if (point.meta.asym == 'clone') {
             point.meta.skip = true
         }
         return [mirrored_name, mp]
diff --git a/test/outlines/circles.yaml b/test/outlines/circles.yaml
index f1aaa51..e83e4e7 100644
--- a/test/outlines/circles.yaml
+++ b/test/outlines/circles.yaml
@@ -22,4 +22,4 @@ outlines:
         ref: matrix
         shift: [-10, 10]
       radius: 5
-      mirror: true
\ No newline at end of file
+      asym: both
\ No newline at end of file
diff --git a/test/outlines/polygons.yaml b/test/outlines/polygons.yaml
index 09bf345..7dfc88e 100644
--- a/test/outlines/polygons.yaml
+++ b/test/outlines/polygons.yaml
@@ -25,4 +25,4 @@ outlines:
         - shift: [-10, 15]
         - shift: [5, -10]
         - shift: [-10, 0]
-      mirror: true
\ No newline at end of file
+      asym: both
\ No newline at end of file
diff --git a/test/outlines/rectangles.yaml b/test/outlines/rectangles.yaml
index df2cab0..2982e5e 100644
--- a/test/outlines/rectangles.yaml
+++ b/test/outlines/rectangles.yaml
@@ -23,4 +23,4 @@ outlines:
         ref: matrix
         shift: [-10, 10]
       size: 10
-      mirror: true
\ No newline at end of file
+      asym: both
\ No newline at end of file