diff --git a/bu4/combinatory/lic.py b/bu4/combinatory/lic.py
index 4f1114e..e53b36a 100644
--- a/bu4/combinatory/lic.py
+++ b/bu4/combinatory/lic.py
@@ -1,17 +1,18 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
 from bu4.combinatory.lcombinatory import LCombinatory
+from bu4.encoding.codes import CODE_CMBI
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.evaluation.constructs.evalue import EValue
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
 from bu4.linkable.evaluation.elvtype import elvtype
-from bu4.parsing.codes import CODE_CMBI
+from bu4.linking.constructs.linked import Linked
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('EIC', 'IIC', 'XII', 'LIC',)
+__all__ = ('EIC', 'IIC', 'XII', 'LIC', 'XLI',)
 
 
 class EIC(EValue):
@@ -51,3 +52,8 @@ class LIC(LCombinatory):
 
     def __str__(self):
         return f'I'
+
+
+class XLI(CodeExtension[Linked], code=CODE_CMBI):
+    def apply(self) -> TransformState[Linked]:
+        return TransformFinished(LIC())
diff --git a/bu4/combinatory/lkc.py b/bu4/combinatory/lkc.py
index 5bd8508..8015ad0 100644
--- a/bu4/combinatory/lkc.py
+++ b/bu4/combinatory/lkc.py
@@ -1,18 +1,19 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
 from bu4.combinatory.lcombinatory import LCombinatory
+from bu4.encoding.codes import CODE_CMBK
 from bu4.evaluation.constructs.edelayed import EDelayed
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.evaluation.constructs.evalue import EValue
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
 from bu4.linkable.evaluation.elvtype import elvtype
-from bu4.parsing.codes import CODE_CMBK
+from bu4.linking.constructs.linked import Linked
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('EKC', 'IKC', 'XIK', 'LKC',)
+__all__ = ('EKC', 'IKC', 'XIK', 'LKC', 'XLK',)
 
 
 class EKC(EValue):
@@ -52,3 +53,8 @@ class LKC(LCombinatory):
 
     def __str__(self):
         return f'K'
+
+
+class XLK(CodeExtension[Linked], code=CODE_CMBK):
+    def apply(self) -> TransformState[Linked]:
+        return TransformFinished(LKC())
diff --git a/bu4/combinatory/lsc.py b/bu4/combinatory/lsc.py
index efc0998..610d248 100644
--- a/bu4/combinatory/lsc.py
+++ b/bu4/combinatory/lsc.py
@@ -1,6 +1,7 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
 from bu4.combinatory.lcombinatory import LCombinatory
+from bu4.encoding.codes import CODE_CMBS
 from bu4.evaluation.av.aftervalue import AfterValue
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.evaluation.constructs.evalue import EValue
@@ -9,12 +10,12 @@ from bu4.evaluation.targets.avcall import AVCall
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
 from bu4.linkable.evaluation.elvtype import elvtype
-from bu4.parsing.codes import CODE_CMBS
+from bu4.linking.constructs.linked import Linked
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('ESC', 'ESC1', 'ESC2', 'ISC', 'XIS', 'LSC',)
+__all__ = ('ESC', 'ESC1', 'ESC2', 'ISC', 'XIS', 'LSC', 'XLS',)
 
 
 class ESC2(EValue):
@@ -86,3 +87,8 @@ class LSC(LCombinatory):
 
     def __str__(self):
         return f'S'
+
+
+class XLS(CodeExtension[Linked], code=CODE_CMBS):
+    def apply(self) -> TransformState[Linked]:
+        return TransformFinished(LSC())
diff --git a/bu4/encoding/codes.py b/bu4/encoding/codes.py
new file mode 100644
index 0000000..8bb8007
--- /dev/null
+++ b/bu4/encoding/codes.py
@@ -0,0 +1,16 @@
+#  Copyright (c) PARRRATE T&V 2021. All rights reserved.
+
+CODE_NULL = 0x00
+CODE_CALL = 0x01
+CODE_MAKE = 0x02
+CODE_NAME = 0x03
+CODE_SKIP = 0x04
+CODE_QUOT = 0x05
+CODE_QOPN = 0x06
+CODE_QCLS = 0x07
+CODE_XCPT = 0x08
+CODE_DLYD = 0x09
+
+CODE_CMBI = 0x49
+CODE_CMBK = 0x4b
+CODE_CMBS = 0x53
diff --git a/bu4/indexing/constructs/icall.py b/bu4/indexing/constructs/icall.py
index 94399eb..c831b37 100644
--- a/bu4/indexing/constructs/icall.py
+++ b/bu4/indexing/constructs/icall.py
@@ -1,12 +1,12 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_CALL
 from bu4.evaluation.av.aftervalue import AfterValue
 from bu4.evaluation.constructs.eattachable import EAttachable
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.evaluation.targets.avcall import AVCall
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_CALL
 from bu4.transform.states.aftertransform import AfterTransform
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstart import TransformStart
diff --git a/bu4/indexing/constructs/idelayed.py b/bu4/indexing/constructs/idelayed.py
index a407464..edc5a18 100644
--- a/bu4/indexing/constructs/idelayed.py
+++ b/bu4/indexing/constructs/idelayed.py
@@ -1,11 +1,11 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_DLYD
 from bu4.evaluation.constructs.eattachable import EAttachable
 from bu4.evaluation.constructs.edelayed import EDelayed
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_DLYD
 from bu4.transform.states.aftertransform import AfterTransform
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstart import TransformStart
diff --git a/bu4/indexing/constructs/iexception.py b/bu4/indexing/constructs/iexception.py
index ad6283e..b547280 100644
--- a/bu4/indexing/constructs/iexception.py
+++ b/bu4/indexing/constructs/iexception.py
@@ -1,10 +1,10 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_XCPT
 from bu4.evaluation.constructs.eexception import EException
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_XCPT
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/constructs/ilambda.py b/bu4/indexing/constructs/ilambda.py
index b0cf796..b3097b8 100644
--- a/bu4/indexing/constructs/ilambda.py
+++ b/bu4/indexing/constructs/ilambda.py
@@ -1,10 +1,10 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_MAKE
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eilambda import EILambda
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_MAKE
 from bu4.transform.states.aftertransform import AfterTransform
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstart import TransformStart
diff --git a/bu4/indexing/constructs/iname.py b/bu4/indexing/constructs/iname.py
index f1b8672..b4e87b9 100644
--- a/bu4/indexing/constructs/iname.py
+++ b/bu4/indexing/constructs/iname.py
@@ -1,9 +1,9 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NAME
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_NAME
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/constructs/inull.py b/bu4/indexing/constructs/inull.py
index c040ea3..ad48675 100644
--- a/bu4/indexing/constructs/inull.py
+++ b/bu4/indexing/constructs/inull.py
@@ -1,10 +1,10 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NULL
 from bu4.evaluation.constructs.enull import ENull
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.evaluation.eivtype import eivtype
-from bu4.parsing.codes import CODE_NULL
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/extensions/xicall.py b/bu4/indexing/extensions/xicall.py
index 0b13219..876042e 100644
--- a/bu4/indexing/extensions/xicall.py
+++ b/bu4/indexing/extensions/xicall.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_CALL
 from bu4.indexing.constructs.icall import ICall
 from bu4.indexing.constructs.indexed import Indexed
-from bu4.parsing.codes import CODE_CALL
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/extensions/xidlyd.py b/bu4/indexing/extensions/xidlyd.py
index ea01517..695fd46 100644
--- a/bu4/indexing/extensions/xidlyd.py
+++ b/bu4/indexing/extensions/xidlyd.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_DLYD
 from bu4.indexing.constructs.idelayed import IDelayed
 from bu4.indexing.constructs.indexed import Indexed
-from bu4.parsing.codes import CODE_DLYD
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/extensions/ximake.py b/bu4/indexing/extensions/ximake.py
index 3e22318..a7f5708 100644
--- a/bu4/indexing/extensions/ximake.py
+++ b/bu4/indexing/extensions/ximake.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_MAKE
 from bu4.indexing.constructs.ilambda import ILambda
 from bu4.indexing.constructs.indexed import Indexed
-from bu4.parsing.codes import CODE_MAKE
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
diff --git a/bu4/indexing/extensions/xiname.py b/bu4/indexing/extensions/xiname.py
index 8700c1a..bb2b88d 100644
--- a/bu4/indexing/extensions/xiname.py
+++ b/bu4/indexing/extensions/xiname.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NAME
 from bu4.indexing.constructs.iname import IName
 from bu4.indexing.constructs.indexed import Indexed
-from bu4.parsing.codes import CODE_NAME
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
diff --git a/bu4/indexing/extensions/xinull.py b/bu4/indexing/extensions/xinull.py
index 246ab56..15eef52 100644
--- a/bu4/indexing/extensions/xinull.py
+++ b/bu4/indexing/extensions/xinull.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NULL
 from bu4.indexing.constructs.indexed import Indexed
 from bu4.indexing.constructs.inull import INull
-from bu4.parsing.codes import CODE_NULL
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
diff --git a/bu4/indexing/extensions/xixcpt.py b/bu4/indexing/extensions/xixcpt.py
index 5142b7a..4d49c48 100644
--- a/bu4/indexing/extensions/xixcpt.py
+++ b/bu4/indexing/extensions/xixcpt.py
@@ -1,8 +1,8 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_XCPT
 from bu4.indexing.constructs.iexception import IException
 from bu4.indexing.constructs.indexed import Indexed
-from bu4.parsing.codes import CODE_XCPT
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
diff --git a/bu4/isynced.py b/bu4/isynced.py
index 6ad8ead..89550f3 100644
--- a/bu4/isynced.py
+++ b/bu4/isynced.py
@@ -1,5 +1,6 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.combinatory.tocombinatory import to_combinatory
 from bu4.evaluation.constructs.evalue import EValue
 from bu4.evaluation.sync import sync
 from bu4.linkable.toolchain.parse import parse
@@ -10,10 +11,12 @@ from bu4.transform.transform import transform
 __all__ = ('isynced',)
 
 
-def isynced(source: str) -> EValue:
+def isynced(source: str, *, combinatory=False) -> EValue:
     bsource = transply(source)
     parsed = parse(bsource, standard_extensions)
     linked = transform(parsed.link(set()))
+    if combinatory:
+        linked = transform(to_combinatory(linked))
     indexed = transform(linked.index([]))
     evaluable = indexed.attach([])
     return sync(evaluable)
diff --git a/bu4/linkable/extensions/xcall.py b/bu4/linkable/extensions/xlcall.py
similarity index 82%
rename from bu4/linkable/extensions/xcall.py
rename to bu4/linkable/extensions/xlcall.py
index e910018..e306852 100644
--- a/bu4/linkable/extensions/xcall.py
+++ b/bu4/linkable/extensions/xlcall.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_CALL
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.pcall import PCall
-from bu4.parsing.codes import CODE_CALL
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XCall',)
+__all__ = ('XLCall',)
 
 
-class XCall(CodeExtension[Parsed], code=CODE_CALL):
+class XLCall(CodeExtension[Parsed], code=CODE_CALL):
     def apply(self) -> TransformState[Parsed]:
         return self.readlambda(
             lambda argument: self.readlambdafinished(
diff --git a/bu4/linkable/extensions/xdlyd.py b/bu4/linkable/extensions/xldlyd.py
similarity index 78%
rename from bu4/linkable/extensions/xdlyd.py
rename to bu4/linkable/extensions/xldlyd.py
index f303801..745048f 100644
--- a/bu4/linkable/extensions/xdlyd.py
+++ b/bu4/linkable/extensions/xldlyd.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_DLYD
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.pdelayed import PDelayed
-from bu4.parsing.codes import CODE_DLYD
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XDlyd',)
+__all__ = ('XLDlyd',)
 
 
-class XDlyd(CodeExtension[Parsed], code=CODE_DLYD):
+class XLDlyd(CodeExtension[Parsed], code=CODE_DLYD):
     def apply(self) -> TransformState[Parsed]:
         return self.readlambdafinished(
             lambda value: PDelayed(value)
diff --git a/bu4/linkable/extensions/xmake.py b/bu4/linkable/extensions/xlmake.py
similarity index 80%
rename from bu4/linkable/extensions/xmake.py
rename to bu4/linkable/extensions/xlmake.py
index fa3db52..4656a4f 100644
--- a/bu4/linkable/extensions/xmake.py
+++ b/bu4/linkable/extensions/xlmake.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_MAKE
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.plambda import PLambda
-from bu4.parsing.codes import CODE_MAKE
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XMake',)
+__all__ = ('XLMake',)
 
 
-class XMake(CodeExtension[Parsed], code=CODE_MAKE):
+class XLMake(CodeExtension[Parsed], code=CODE_MAKE):
     def apply(self) -> TransformState[Parsed]:
         name = self.parser.parse_name()
         return self.readlambdafinished(
diff --git a/bu4/linkable/extensions/xname.py b/bu4/linkable/extensions/xlname.py
similarity index 80%
rename from bu4/linkable/extensions/xname.py
rename to bu4/linkable/extensions/xlname.py
index 83650c9..1ddf984 100644
--- a/bu4/linkable/extensions/xname.py
+++ b/bu4/linkable/extensions/xlname.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NAME
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.pname import PName
-from bu4.parsing.codes import CODE_NAME
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XName',)
+__all__ = ('XLName',)
 
 
-class XName(CodeExtension[Parsed], code=CODE_NAME):
+class XLName(CodeExtension[Parsed], code=CODE_NAME):
     def apply(self) -> TransformState[Parsed]:
         return TransformFinished(PName(self.parser.parse_name()))
diff --git a/bu4/linkable/extensions/xnull.py b/bu4/linkable/extensions/xlnull.py
similarity index 79%
rename from bu4/linkable/extensions/xnull.py
rename to bu4/linkable/extensions/xlnull.py
index fbd177f..f33dfb2 100644
--- a/bu4/linkable/extensions/xnull.py
+++ b/bu4/linkable/extensions/xlnull.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_NULL
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.pnull import PNull
-from bu4.parsing.codes import CODE_NULL
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XNull',)
+__all__ = ('XLNull',)
 
 
-class XNull(CodeExtension[Parsed], code=CODE_NULL):
+class XLNull(CodeExtension[Parsed], code=CODE_NULL):
     def apply(self) -> TransformState[Parsed]:
         return TransformFinished(PNull())
diff --git a/bu4/linkable/extensions/xqopn.py b/bu4/linkable/extensions/xlqopn.py
similarity index 72%
rename from bu4/linkable/extensions/xqopn.py
rename to bu4/linkable/extensions/xlqopn.py
index 9e8b414..c31fefc 100644
--- a/bu4/linkable/extensions/xqopn.py
+++ b/bu4/linkable/extensions/xlqopn.py
@@ -1,13 +1,13 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_QOPN, CODE_QCLS
 from bu4.linkable.constructs.parsed import Parsed
-from bu4.parsing.codes import CODE_QOPN, CODE_QCLS
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XQopn',)
+__all__ = ('XLQopn',)
 
 
-class XQopn(CodeExtension[Parsed], code=CODE_QOPN):
+class XLQopn(CodeExtension[Parsed], code=CODE_QOPN):
     def apply(self) -> TransformState[Parsed]:
         return self.endswith(CODE_QCLS, 'quot expected')
diff --git a/bu4/linkable/extensions/xquot.py b/bu4/linkable/extensions/xlquot.py
similarity index 74%
rename from bu4/linkable/extensions/xquot.py
rename to bu4/linkable/extensions/xlquot.py
index 1d2c189..3ed96b7 100644
--- a/bu4/linkable/extensions/xquot.py
+++ b/bu4/linkable/extensions/xlquot.py
@@ -1,13 +1,13 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_QUOT
 from bu4.linkable.constructs.parsed import Parsed
-from bu4.parsing.codes import CODE_QUOT
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XQuot',)
+__all__ = ('XLQuot',)
 
 
-class XQuot(CodeExtension[Parsed], code=CODE_QUOT):
+class XLQuot(CodeExtension[Parsed], code=CODE_QUOT):
     def apply(self) -> TransformState[Parsed]:
         return self.endswith(CODE_QUOT, 'quot expected')
diff --git a/bu4/linkable/extensions/xskip.py b/bu4/linkable/extensions/xlskip.py
similarity index 76%
rename from bu4/linkable/extensions/xskip.py
rename to bu4/linkable/extensions/xlskip.py
index e3e8b04..922fec2 100644
--- a/bu4/linkable/extensions/xskip.py
+++ b/bu4/linkable/extensions/xlskip.py
@@ -1,14 +1,14 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_SKIP
 from bu4.linkable.constructs.parsed import Parsed
-from bu4.parsing.codes import CODE_SKIP
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.parsing.states.parsingread import ParsingRead
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XSkip',)
+__all__ = ('XLSkip',)
 
 
-class XSkip(CodeExtension[Parsed], code=CODE_SKIP):
+class XLSkip(CodeExtension[Parsed], code=CODE_SKIP):
     def apply(self) -> TransformState[Parsed]:
         return ParsingRead(self.parser)
diff --git a/bu4/linkable/extensions/xxcpt.py b/bu4/linkable/extensions/xlxcpt.py
similarity index 80%
rename from bu4/linkable/extensions/xxcpt.py
rename to bu4/linkable/extensions/xlxcpt.py
index 18808ad..0b0deaf 100644
--- a/bu4/linkable/extensions/xxcpt.py
+++ b/bu4/linkable/extensions/xlxcpt.py
@@ -1,15 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
+from bu4.encoding.codes import CODE_XCPT
 from bu4.linkable.constructs.parsed import Parsed
 from bu4.linkable.constructs.pexception import PException
-from bu4.parsing.codes import CODE_XCPT
 from bu4.parsing.extensions.CodeExtension import CodeExtension
 from bu4.transform.states.transformfinished import TransformFinished
 from bu4.transform.states.transformstate import TransformState
 
-__all__ = ('XXcpt',)
+__all__ = ('XLXcpt',)
 
 
-class XXcpt(CodeExtension[Parsed], code=CODE_XCPT):
+class XLXcpt(CodeExtension[Parsed], code=CODE_XCPT):
     def apply(self) -> TransformState[Parsed]:
         return TransformFinished(PException(self.parser.parse_name()))
diff --git a/bu4/linkable/toolchain/stdext.py b/bu4/linkable/toolchain/stdext.py
index acaeaed..c1c3be2 100644
--- a/bu4/linkable/toolchain/stdext.py
+++ b/bu4/linkable/toolchain/stdext.py
@@ -1,25 +1,25 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
-from bu4.linkable.extensions.xcall import XCall
-from bu4.linkable.extensions.xdlyd import XDlyd
-from bu4.linkable.extensions.xmake import XMake
-from bu4.linkable.extensions.xname import XName
-from bu4.linkable.extensions.xnull import XNull
-from bu4.linkable.extensions.xqopn import XQopn
-from bu4.linkable.extensions.xquot import XQuot
-from bu4.linkable.extensions.xskip import XSkip
-from bu4.linkable.extensions.xxcpt import XXcpt
+from bu4.linkable.extensions.xlcall import XLCall
+from bu4.linkable.extensions.xldlyd import XLDlyd
+from bu4.linkable.extensions.xlmake import XLMake
+from bu4.linkable.extensions.xlname import XLName
+from bu4.linkable.extensions.xlnull import XLNull
+from bu4.linkable.extensions.xlqopn import XLQopn
+from bu4.linkable.extensions.xlquot import XLQuot
+from bu4.linkable.extensions.xlskip import XLSkip
+from bu4.linkable.extensions.xlxcpt import XLXcpt
 
 __all__ = ('standard_extensions',)
 
 standard_extensions = (
-    XNull,
-    XCall,
-    XMake,
-    XName,
-    XSkip,
-    XQuot,
-    XQopn,
-    XXcpt,
-    XDlyd,
+    XLNull,
+    XLCall,
+    XLMake,
+    XLName,
+    XLSkip,
+    XLQuot,
+    XLQopn,
+    XLXcpt,
+    XLDlyd,
 )
diff --git a/bu4/linkable/toolchain/transply.py b/bu4/linkable/toolchain/transply.py
index 827c787..77f0136 100644
--- a/bu4/linkable/toolchain/transply.py
+++ b/bu4/linkable/toolchain/transply.py
@@ -2,7 +2,7 @@
 
 from io import BytesIO
 
-from bu4.parsing.codes import *
+from bu4.encoding.codes import *
 
 __all__ = ('transply',)
 
diff --git a/bu4/parsing/codes.py b/bu4/parsing/codes.py
deleted file mode 100644
index 17f04f6..0000000
--- a/bu4/parsing/codes.py
+++ /dev/null
@@ -1,15 +0,0 @@
-#  Copyright (c) PARRRATE T&V 2021. All rights reserved.
-
-CODE_NULL = 0
-CODE_CALL = 1
-CODE_MAKE = 2
-CODE_NAME = 3
-CODE_SKIP = 4
-CODE_QUOT = 5
-CODE_QOPN = 6
-CODE_QCLS = 7
-CODE_XCPT = 8
-CODE_DLYD = 9
-CODE_CMBI = 10
-CODE_CMBK = 11
-CODE_CMBS = 12
diff --git a/bu4/tracing/deep_trace.py b/bu4/tracing/deep_trace.py
new file mode 100644
index 0000000..5ae7f56
--- /dev/null
+++ b/bu4/tracing/deep_trace.py
@@ -0,0 +1,30 @@
+#  Copyright (c) PARRRATE T&V 2021. All rights reserved.
+
+from collections import deque
+
+from bu4.tracing.probe import Probe
+from bu4.tracing.trace import trace
+
+__all__ = ('deep_trace',)
+
+
+def deep_trace(sysx, *, length=1000, depth=10000):
+    hist = []
+    queue = deque([(0, 0, sysx)])
+    for trace_index in range(1, length + 1):
+        hist.append(trace_index)
+        if not queue:
+            break
+        tab, parent, evaluable = queue.popleft()
+        hist.append(parent)
+        for _ in range(depth):
+            evaluable = evaluable.next()
+        _probe_index, probe = trace(evaluable)
+        hist.append(_probe_index)
+        if isinstance(probe, Probe):
+            start, list_ = probe.start_and_list()
+            hist.append(start)
+            queue.extend((tab + 1, trace_index, deeper_evaluable) for deeper_evaluable in list_)
+        else:
+            hist.append(None)
+    return hist
diff --git a/bu4/tracing/probe.py b/bu4/tracing/probe.py
index 7b1231a..14bd525 100644
--- a/bu4/tracing/probe.py
+++ b/bu4/tracing/probe.py
@@ -3,10 +3,13 @@
 from bu4.evaluation.constructs.evaluable import Evaluable
 from bu4.evaluation.constructs.evalue import EValue
 
-__all__ = ('Probe', 'ProbeA',)
+__all__ = ('Probe',)
 
 
 class Probe(EValue):
+    def __new__(cls, *args, **kwargs):
+        return object.__new__(ProbeA if cls == Probe else cls)
+
     def call(self, argument: Evaluable) -> Evaluable:
         return ProbeB(self, argument)
 
diff --git a/bu4/tracing/trace.py b/bu4/tracing/trace.py
index cd48eeb..e973fdb 100644
--- a/bu4/tracing/trace.py
+++ b/bu4/tracing/trace.py
@@ -8,7 +8,7 @@ from bu4.evaluation.constructs.evalue import EValue
 from bu4.evaluation.sync import sync
 from bu4.indexing.evaluation.eilambda import EILambda
 from bu4.linkable.evaluation.ellambda import ELLambda
-from bu4.tracing.probe import ProbeA
+from bu4.tracing.probe import Probe
 
 __all__ = ('trace', 'probe_index_reset',)
 
@@ -21,7 +21,7 @@ def trace(lambda_: EValue):
     while True:
         if not isinstance(lambda_, (ELLambda, EILambda, EIC, EKC, ESC, ESC1, ESC2, EDelayed)):
             return size, lambda_
-        lambda_ = sync(lambda_.call(ProbeA(_probe_index)))
+        lambda_ = sync(lambda_.call(Probe(_probe_index)))
         _probe_index += 1
         size += 1
 
diff --git a/main.py b/main.py
index 804d2d2..a2db548 100644
--- a/main.py
+++ b/main.py
@@ -1,56 +1,15 @@
 #  Copyright (c) PARRRATE T&V 2021. All rights reserved.
 
 import random
-from collections import deque
 
 from bu4.common_interface import with_common_interface
 from bu4.evaluation.constructs.proxy import antiproxy, eproxy
 from bu4.evaluation.sync import sync
 from bu4.isynced import isynced as synced
-from bu4.linkable.toolchain.parse import parse
 from bu4.linkable.toolchain.readfile import readfile
-from bu4.linkable.toolchain.stdext import standard_extensions
-from bu4.linkable.toolchain.transply import transply
-from bu4.combinatory.tocombinatory import to_combinatory
-from bu4.tracing.probe import Probe
-from bu4.tracing.trace import trace
-from bu4.transform.transform import transform
+from bu4.tracing.deep_trace import deep_trace
 from timesample import TimeSample
 
-
-def deep_trace(sysx):
-    hist = []
-    queue = deque([(0, 0, sysx)])
-    for trace_index in range(1, 1000 + 1):
-        hist.append(trace_index)
-        if not queue:
-            break
-        tab, parent, evaluable = queue.popleft()
-        hist.append(parent)
-        for _ in range(10000):
-            evaluable = evaluable.next()
-        _probe_index, probe = trace(evaluable)
-        hist.append(_probe_index)
-        # prefix = ('.', '  ' * tab, parent, trace_index)
-        if isinstance(probe, Probe):
-            start, list_ = probe.start_and_list()
-            hist.append(start)
-            for i in range(len(list_)):
-                for _ in range(10000):
-                    list_[i] = list_[i].next()
-            # TimeSample.print(*prefix, _probe_index, 'probe', start, f'[ {" ; ".join(map(str, list_))} ]')
-            queue.extend((tab + 1, trace_index, deeper_evaluable) for deeper_evaluable in list_)
-        else:
-            hist.append(None)
-            # TimeSample.print(*prefix, '...')
-    return hist
-
-
-print(transform(to_combinatory(transform(parse(transply(
-    '/[b]/[a](x)(y)/[x][y]'
-), standard_extensions).link({b'a', b'b'})))))
-
-
 with TimeSample('all'):
     with TimeSample('sys0'):
         with TimeSample('compilation'):