* Bump API patch number and header version number to 53 for this update.
Github Issues:
Internal Issues:
* Clarify mappings of coordinates for mutable, compatible image views in
slink:VkImageViewCreateInfo (internal issue 815).
* Make ename:VK_BIND_SFR_BIT require a logical device with multiple
physical devices, so that standard sparse image block dimensions are
only required on systems that support multi-GPU (internal issue 835).
* Convert all files from use of // refBegin .. // refEnd comments to
delimit ref pages, to use of open blocks, and update style guide
accordingly (internal issue 839).
* Add valid usage for slink:VkWriteDescriptorSet when performing updates
to a ename:VK_STORAGE_IMAGE descriptor with layout
ename:VK_IMAGE_LAYOUT_GENERAL.
* Add a hack to the validity generator script to support an odd
interaction between flink:vkCmdFillBuffer and an extension (internal
issue 853).
* Remove redundant text describing slink:VkBufferCreateInfo::pname:usage,
which was already covered by implicit valid usage (internal issue 854).
* Update implicit validity generator script to properly handle the
pname:sType and pname:pNext members of "returnedonly" structures
(internal issue 874).
* Note that slink:VkApplicationInfo::pname:pApplicationName &
slink:VkApplicationInfo::pname:pEngineName are optional, and add missing
implicit valid usage statements for flink:vkDestroyInstance.
* Added missing valid usage for flink:vkCmdWriteTimestamp to require a
timestamp query pool.
* Simplify and/or split "`non-atomic`" valid usage statements.
New Extensions:
* `VK_AMD_gpu_shader_int16`
* `VK_EXT_blend_operation_advanced`
* `VK_EXT_sampler_filter_minmax`
* `VK_NV_framebuffer_mixed_samples`
-----------------------------------------------------
Note: the 1.0.52 spec wasn't published on github, so the 1.0.53 release
combines both change sets.
-----------------------------------------------------
Change log for June 13, 2017 Vulkan 1.0.52 spec update:
* Bump API patch number and header version number to 52 for this update.
Github Issues:
Internal Issues:
* Clarify behavior when non-coherent memory has
<<memory-device-unmap-does-not-flush, not been flushed before being
unmapped>> (internal issue 819).
* Fix description of code:WorkgroupSize builtin to note it decorates an
object, not a variable (internal issue 836).
* Fix asciidoc attributes so that trailing '{plus}' symbols in [eq] style
equations are rendered properly (internal issue 845).
* Add language to the "`Extension Handles, Objects, Enums, and Typedefs`"
section of the Procedures and Conventions document stating that any new
handle type requires a corresponding entry in the elink:VkObjectType
enumerated type (internal issue 856).
* Update style guide to use slink macro for Vulkan handle type names, and
define narrow conditions under which to use the *name and *text macros
instead of *link (internal issue 886).
* Add a dependency of the <<VK_KHX_device_group,VK_KHX_device_group>>
extension on VK_KHX_device_group_creation to +vk.xml+ and the extension
appendix.
* Change the copyright on Vulkan specification asciidoc *source* files to
CC-BY 4.0, and update the proprietary Khronos copyright applied to the
generated *output* formats (internal issue 327). This enables broader
re-use and modification of the Vulkan specification sources, while not
affecting the Reciprocal IP License between Vulkan Adopters and Working
Group Members.
New Extensions:
* `VK_NV_fill_rectangle`
* `VK_NV_fragment_coverage_to_color`
* Bump API patch number and header version number to 50 for this update.
Github Issues:
* Fix numerous minor issues with the VK_EXT_debug_report extension (public
issues 478, 483, 486, 489, 490).
Internal Issues:
* Update flink:vkAllocateDescriptorSets to specify conditions under which
to return ename:VK_ERROR_FRAGMENTED_POOL or
ename:VK_ERROR_OUT_OF_POOL_MEMORY instead of
out-of-host/out-of-device-memory, and improve the
<<fundamentals-errorcodes, description of those errors (internal issue
654).
* Add a NOTE documenting that flink:vkAcquireNextImageKHR can only signal
a single semaphore, and how to deal with that when multiple physical
devices in a logical device need to wait on it (internal issue 730).
* Improve description of pname:pNext chains of
slink:VkPhysicalDeviceImageFormatInfo2KHR and
slink:VkImageFormatProperties2KHR (internal issue 814).
* Clean up math markup issues in the <<textures, Image Operations>>
chapter (internal issue 818).
* Update validusage target to use more robust code for preprocessing, by
making direct use of Asciidoctor's preprocessor. Added uniqueItems check
to JSON vu schema and add clean_validusage target (internal issue 826).
* Update style guide to prohibit writing non-self-contained (on a single
bullet point) Valid Usage statements, and modify offending Valid Usage
statements in the Specification to match, to assist with automatic
extraction for the validation layers (internal issue 828).
* Add ename:VK_VALIDATION_CHECK_SHADERS_EXT to elink:VkValidationCheckEXT
of the `VK_EXT_validation_flags` extension, to selectively disable
shader validation.
* Remove duplicate valid usage statement for slink:VkImageMemoryBarrier.
* Modify reflow.py script to place VUID tag anchors standalone on a line
following their corresponding bullet point, and reflow the spec text
accordingly (this had been pending since the initial tag deployment).
New Extensions:
* `VK_AMD_texture_gather_bias_lod`
* Bump API patch number and header version number to 49 for this update.
Github Issues:
* Modify reference page extraction script to make internal links to spec
anchors refer to the core specification instead of being dangling links
(public issue 455).
* Fix GL_KHR_vulkan_glsl typo and add a nor-normative mapping to the newly
published StorageBuffer class (public issue 466).
* Both flink:vkEnumerateInstanceExtensionProperties and
flink:vkEnumerateDeviceExtensionProperties return
ename:VK_ERROR_LAYER_NOT_PRESENT, which covers the error case of an
application providing a layer name that wasn't returned by
ftext:vkEnumerate{Instance|Device}LayerProperties (public issue 487).
* The specification for flink:VkApplicationInfo::apiVersion says that the
driver must return ename:VK_ERROR_INCOMPATIBLE_DRIVER in the case that
pname:apiVersion specifies a non-supported version. That means that the
valid usage should not also state that, and so the VU statement is
removed. The VU had language about "`an effective substitute`" that
would have been lost, and so it was moved to the pname:apiVersion
description (public issue 488).
Internal Issues:
* Modify implicit validity generator script to assign asciidoc anchors to
all valid usage statements it generates, and reflow.py script to insert
Valid Usage ID (VUID) tags into the specification source files for
explicit valid usage statements. This has no semantic effects on the
specification, but will support the validation layer's detection of
valid usage violations and allow it to link into the corresponding part
of the specification (internal issue 583).
* Assign VUID tags to all explicit VU statements and document
the process and tag format in the style guide (internal issue 583).
* Clarify the rules of whether to structure new functionality as instance
extensions, device extensions, or both in the
<<extended-functionality-instance-extensions-and-devices, Instance
Extensions and Device Extensions>> section (internal issue 749).
* Require that SPIR-V run-time arrays are only used with the
code:BufferBlock decoration (internal issue 750).
* Fix implicit and explicit valid usage statements for
slink:VkWriteDescriptorSet::pname:dstSet (internal issue 767)
* Fix SPIR-V code sample for ename:VK_DESCRIPTOR_TYPE_UNIFORM_TEXEL_BUFFER
in the <<descriptorsets-uniformtexelbuffer, Uniform Texel Buffer>>
section (internal issue 770).
* Clarify that disabling depth testing also disables depth writes in the
<<fragops-ds-state, Depth and Stencil Operations>> section (internal
issue 775).
* flink:VkDescriptorImageInfo::pname:imageLayout must match the actual
imageLayout at the time the image is accessed. This was in the spec
text, but needed an associated valid usage statement.
* Note that only 32-bit atomic operations are supported in the
<<spirvenv-module-validation, Validation Rules within a Module>>
section.
* Note that code:UniformConstant variables must not have initializers in
the <<spirvenv-module-validation, Validation Rules within a Module>>
section.
* Add a new elink:VkObjectType enumeration to the core API, promoted from
elink:VkDebugObjectTypeEXT, since it is used for much more than just the
debug_report extension.
New Extensions:
* `VK_KHR_get_surface_capabilities2`
* `VK_KHR_shared_presentable_image`
* Bump API patch number and header version number to 39 for this update.
Github Issues:
* Clarified that only accesses via the specified buffer/image subresource
ranges are included in the access scopes (public issue 306).
* Add missing valid usage statements for flink:vkCreateComputePipelines
and flink:vkCreateGraphicsPipelines (public issue 427).
Internal Issues:
* Add a Note to the <<invariance,Invariance>> appendix about a difference
between OpenGL and Vulkan with regards to how primitives derived from
offsets are handled (internal issue 355).
* Add the +<<VK_KHR_get_physical_device_properties2>>+,
+<<VK_KHR_maintenance1>>+, and +<<VK_KHR_shader_draw_parameters>>+
extensions (internal issue 448).
* Add the +<<VK_EXT_shader_subgroup_vote>>+ and
+<<VK_EXT_shader_subgroup_ballot>>+ extensions (internal issue 449).
* Update the texture level-of-detail equation in the
<<textures-scale-factor,Scale Factor Operation>> section to better
approximate the ellipse major and minor axes (internal issue 547).
* Forbid non-explicitly allowed uses of interface decorations in the
introduction to the <<interfaces,Shader Interfaces>> chapter (internal
issue 607).
* Replace use of MathJax with KaTeX, for improved load-time performance as
well as avoiding the scrolling-and-scrolling behavior due to MathJax
asynchronous rendering when loading at an anchor inside the spec. This
change also requires moving to HTML5 output for the spec instead of
XHTML, and there is a visible difference in that the chapter navigation
index is now in a scrollable sidebar instead of at the top of the
document. We may or may not retain the nav sidebar based on feedback
(internal issue 613).
* Improve consistency of markup and formatting in extension appendices
(internal issue 631).
Other Issues:
* Add explicit valid usage statements to slink:VkImageCopy requiring that
the source and destination layer ranges be contained in their respective
source and destination images.
* Add valid usage language for swapchain of flink:vkAcquireNextImage. If
the swapchain has been replaced, then it should not be passed to
flink:vkAcquireNextImage.
* Add a valid usage statement to flink:vkCreateImageView, that the image
must have been created with an appropriate usage bit set.
* Noted that slink:VkDisplayPresentInfoKHR is a valid extension of
slink:VkPresentInfoKHR in the <<wsi_swapchain,WSI Swapchain>> section.
* Update valid usage for flink:vkCmdSetViewport and flink:vkCmdSetScissor
to account for the multiple viewport feature. If the feature is not
enabled, the parameters for these functions have required values that
are defined in the <<features-features-multiViewport,multiple
viewports>> section of the spec but were not reflected in the valid
usage text for these functions.
* Add the +<<VK_EXT_swapchain_colorspace>>+ extension defining common
color spaces.
* Bump API patch number and header version number to 35 for this update.
Github Issues:
* Document in the <<memory-device-hostaccess,Host Access>> section that
mapping and unmapping does not invalidate or flush the mapped memory
(public issues 27, 126).
* Redefine the entire <<synchronization>> chapter in terms of consistent
and well defined terminology, that's called out at the start of the
chapter. This terminology is applied equally to all synchronization
types, including subpass dependencies, submissions, and much of the
implicit ordering stuff dotted around the spec. Key terms are laid out
in the <<synchronization-dependencies,Execution and Memory
Dependencies>> section at the top of the rewritten chapter (public
issues 128, 131, 132, 217, 299, 300, 302, 306, 322, 346, 347, 371, 407).
* Specify order of submission for batches in the
<<vkQueueSubmit,vkQueueSubmit>> and
<<vkQueueBindSparse,vkQueueBindSparse>> commands (public issue 371).
* Add valid usage statements to each of the WSI extension sections
indicating that the WSI-specific structure parameters must be valid, and
remove automatically generated valid usage statements now covered by the
manual sections (public issue 383).
* Clarify render pass compatibility for flink:vkCmdExecuteCommands (public
issue 390).
Internal Issues:
* Update +vk.xml+ to make previously explicit valid usage statements for
<<vkDebugReportMessageEXT,vkDebugReportMessageEXT>> implicit instead
(internal issue 553).
* Add valid usage statement for slink:VkCreateImageInfo preventing
creation of 1D sparse images (internal issue 573).
* Fix Python scripts to always read/write files in utf-8 encoding, and a
logic error in reflib.py which could cause a fatal error for
malstructured asciidoc (internal issues 578, 586).
* Bump API patch number and header version number to 33 for this update.
Github Issues:
* Added implicit external synchronization parameters to
vkBegin/EndCommandBuffer, and fixed missing command pool host
synchronization from per-command lists (public issue 398).
* Started using git tags including the spec release number, such as
'v1.0.32-core', instead of tags including the date of release, such as
'v1.0-core-20161025' (public issue 405).
Internal Issues:
* Add validity constraint for
slink:VkImportMemoryWin32HandleInfoNV::pname:handle (internal issue
#480).
* Add scripts to compare two Vulkan HTML specifications, derived from W3
htmldiff service (internal issue 525).
* Relax requirement that memoryTypeBits can't depend on format, to allow
it to differ only for depth/stencil formats (internal issue 544).
* Add a new generator script to create a simple extension loader for
Vulkan based on +vk.xml+ (internal issue 558).
* Add the overlooked requirement that buffer and image memory
alignment requirements must be a power of two in the
<<resources-association,Resource Memory Association>> section
(internal issue 569).
Other Issues:
* Add a naming rule to the style guide for members of extension structures
defining array lengths which are the same as array lengths of the core
structure they are chained from.
* Add a new generator to create a simple extension loader in
+src/ext_loader/vulkan_ext.[ch]+ from +vk.xml+. This code can be
included in your project, and is expected to be packaged in the Vulkan
SDK provided by LunarG in the future.
* Bump API patch number and header version number to 29 for this update.
Github Issues:
* Remove redundant constraint on
slink:VkCommandBufferInheritanceInfo::pname:queryFlags (public issue
224).
* Fix typo and remove link in Note in the
<<extended-functionality-instance-extensions-and-devices, Instance
Extensions and Device Extensions>> section (public issue 359).
* Fix erroneous validation statement for the pname:layout member of
slink:VkComputePipelineCreateInfo (public issue 362).
Internal Issues:
* Restore long figure captions using asciidoc sidebar blocks, due to
restrictions of asciidoc syntax (internal issue 101).
* Replace most latexmath equations with comparable markup in straight
asciidoc, which significantly improves time required to fully load and
process the HTML forms of the Specification. There are known minor font
and alignment inconsistencies with MathJax and PDF rendering of
latexmath equations. Please do not file github issues about these. We
are aware of the inconsistencies and will make refinements over time,
while the performance improvements are compelling in at least some major
browsers (internal issue 313).
* Move handcoded validity statements from +vk.xml+ into the Specification
body, easing work in the single-branch model. Specify the distinction
between these explicit statements, and the implicit validity statements
inferred from vk.xml. Validity statements now appear in two blocks for
each command and structure - handcoded "Valid Usage" and the implicit
"Valid Usage (Implicit)" (internal issue 392).
* Add the +returnedonly="false"+ attribute to WSI output structures,
removing incorrectly generated implicit validity statements for
slink:VkDisplayPropertiesKHR, slink:VkDisplayPlanePropertiesKHR,
slink:VkDisplayModePropertiesKHR, slink:VkDisplayPlaneCapabilitiesKHR,
slink:VkSurfaceCapabilitiesKHR, and slink:VkSurfaceFormatKHR structures
(internal issue 486).
* Update slink:VkImageLayout to require the
ename:VK_IMAGE_USAGE_SAMPLED_BIT be set for sampled depth/stencil images
(internal issue 487).
* Use an explicit format specifier string for the date command invocation
in the +Makefile+ instead of the shorthand -R option, which doesn't work
on BSD and MaxOS X date commands (internal issue 500).
Other Issues:
* Use the terms ``allocation scope'' and ``extension scope'' instead of
just ``scope'', and add them to the glossary.
* Bump API patch number and header version number to 28 for this update.
Github Issues:
* Minor spelling and typography cleanup, add definitions of
ename:VK_FALSE and ename:VK_TRUE as just what their names say
(public issues 220, 318, 325, 365; internal issues 451, 496)
* Clarify that the pname:maxDescriptorSet limits in the
<<features-limits-required,Required Limits>> table are n *
maxPerStage limit (where n=number of supported stages) (public issue
254).
* Minor cleanup to <<boilerplate-platform-macros,Platform-Specific
Macro Definitions>> appendix (public issue 314).
* Add valid usage statement to slink:VkPipelineLayoutCreateInfo
disallowing multiple push constant ranges for the same shader stage
(public issue 340).
* Clarify the elink:VkSharingMode description of what executing the
"same" barriers means in case of ownership transfer (public issue
347).
* Rename copyright.txt and add COPYING.md to try and reduce confusion
about applicable copyrights (public issue 350).
* Extend the table in the <<boilerplate-wsi-header, Window System-Specific
Header Control>> section to describe the external headers included when
each etext:VK_USE_PLATFORM_* macro is defined (public issue 376).
Internal Issues:
* Add "Revision History" to the PDF outputs following the table of
contents, to match HTML outputs (internal issue 43).
* Clarified that flink:vkMapMemory may fail due to virtual address
space limitations (internal issue 346).
* Add +refBody+ comment markup for ref page autoextraction when required
(internal issue 400).
* Document proper use of "mipmap" and "mip" in the style guide API
naming rules, matching the spelling rules (internal issue 471).
* Tweak the <<extensions,Layers and Extensions>> appendix to note that
the Specification may be built with arbitrary combinations of
extensions (internal issue 483).
* Remove incorrect statement allowing
slink:VkClearAttachment::pname:colorAttachment to be >=
slink:VkSubpassDescription::pname:colorAttachmentCount (internal
issue 488).
* The <<features-limits-viewportboundsrange,viewportBoundsRange>> is
expressed in terms of the pname:maxViewportDimensions but this is
actually two values. Clarify that it's based on the larger of the two
(if they differ) (internal issue 499).
Other Issues:
* Reflowed text of the entire spec using the 'reflow' Makefile gater,
to (hopefully) reduce future internal git churn as edits are made
and extensions added in return for one-time pain. This has no
perceptible change on the spec outputs but considerable changes on
the asciidoc source (internal issue 367).
* Bump API patch number and header version number to 27 for this update.
Github Issues:
* Weaken flink:vkGetPipelineCacheData invariance conditions; previous
conditions were stronger than agreed and can't be guaranteed (public
issue 280).
* Add link to "Vulkan Loader Specification and Architecture Overview"
document to Normative References section (public issue 359).
Internal Issues:
* Be more clear in the <<interfaces-resources-layout-std140, uniform
buffer layout>> section that block offsets can be out of order
(internal issue 396).
* Document that extension authors should add support for their extensions
to the validation layers (internal issue 398).
* Clarify that the valid range of depth clear values should be limited
to the 0..1 range and that copies to depth aspect must also be in this
range (internal issue 412).
* Specify ``a'' vs. ``an'' use in the style guide (internal issue 432).
* Increase the maximum pname:nonCoherentAtomSize value in the
<<features-limits-required,Required Limits>> section from 128 to 256
(internal issue 435).
* Fix vk_platform.h for compiler errors on some Android platforms
(internal issue 441).
* Clarify that slink:VkPhysicalDeviceFeatures::pname:pEnabledFeatures ==
`NULL` disables all features, including the "required" feature
pname:robustBufferAccess (internal issue 479).
Other Issues:
* Expand style guide and make it more self-consistent.
* Use ISO 8601 date format everywhere.
* Emphasise the correct way of using
slink:VkSurfaceCapabilitiesKHR::pname:maxImageCount.
* Added +VK_EXT_validation_flags+ extension for validation flag mechanism.
* Fix an <<credits,author credit>> to include their current employer.
* Bump API patch number and header version number to 26 for this update.
Github Issues:
* Bring sample code in the +VK_KHR_surface+ and +VK_KHR_swapchain+
extension summary appendices up to date, and note they will be replaced
with pointers to the LunarG SDK examples in the future (public issue
279).
* Add a new <<fundamentals-commandsyntax-results-lifetime,Lifetime of
Retrieved Results>> section specifying that ftext:vkGet* and
ftext:VkEnumerate* results are invariant unless otherwise specified, and
specify behavior for individual commands which are not invariant (public
issue 280).
* Remove conflicting definition of
slink:VkDisplayPlaneCapabilitiesKHR::pname:maxSrcPosition and clean up
language of the remaining definition (public issue 351).
* Fix many minor spelling errors and add rules to the style guide to
prevent recurrences (public issue 352).
Internal Issues:
* Remove redundant descriptions of the etext:VK_USE_PLATFORM_* macros from
the <<wsi,Window System Integration>> chapter in favor of the
description in the <<boilerplate-wsi-header,Window System-Specific
Header Control>> appendix (internal issue 6).
* Replace misleading 'can: be destroyed when not X' with more correct
'must: not be destroyed while X' in the
<<fundamentals-objectmodel-lifetime,Object Lifetime>> section. Disallow
destroying a pipeline layout while a command buffer using it is
recording (internal issue 241).
* Clarify that ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT is valid for
all images used as attachments in elink:VkImageUsageFlagBits and the
slink:VkImageLayout validity language (internal issue 320).
* Note that <<extended-functionality-layers,Layers>> may wrap object
handles, but that this is a generally discouraged. A link to additional
information in the documentation for layer authors is provided (issue
398)
* Replace the mustnot: and shouldnot: macros with equivalent must: not and
should: not to get rid of non-English words while still highlighting
normative language (internal issue 407).
* Disallow creating multisampled images with
ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT in the slink:VkImageLayout
validity language and the <<features-supported-sample-counts,Supported
Sample Counts>> section (internal issue 445).
* Fix typo so that flink:vkCmdDrawIndexedIndirect is defined in terms of
flink:vkCmdDrawIndexed rather than flink:vkCmdDrawIndirect (internal
issue 446).
* Reorganize the per-extension information sections to all be in the
<<extensions,Layers & Extensions>> appendix. Also fix a typo in
+VK_IMG_filter_cubic+ which incorrectly identified it as a +KHR+
extension (internal issue 461).
Other Issues:
* Use asciidoc markup instead of latexmath to simplify diagrams in the
<<features-formats-non-packed,byte mapping tables>> for color formats.
* Fix a markup problem with the wildcarded enumerant names in a NOTE in
the <<textures-texel-replacement,Texel Replacement>> section.
* Fix missing attributes in the XML interface for
elink:VkExternalMemoryHandleTypeFlagBitsNV and
elink:VkExternalMemoryFeatureFlagBitsNV (KhronosGroup/Vulkan-Hpp issue
#25)
* Cleanup reference page builds so only core pages are built for releases.
* Bump API patch number and header version number to 25 for this update.
* Structurally change the specification so that multiple extensions are
included in the +1.0+ git branch, and specifications will include or not
include those extensions at build time based on options passed to the
Makefile. See +doc/specs/vulkan/README.html+ and the ``Layers and
Extensions'' section of the ``Vulkan Documentation and Extensions''
document for more information on this change.
* Register and publish new extensions in the single-branch form:
** +VK_NV_external_memory_capabilities+
** +VK_NV_external_memory+
** +VK_NV_external_memory_win32+
** +VK_NV_win32_keyed_mutex+
Github Issues:
* Clarify description of GetInstanceProcAddr and GetDeviceProcAddr (public
issue 212).
* Add SPIR-V <<textures-operation-validation, instruction validation>> for
single-sampled images (public issue 316).
* Fix spelling of ``tesselation'' in a few places and note it as an
exception to the American spelling rules convention (public issue
327).
* Fix Makefile to create output directory for ``styleguide''
target (public issue 329).
* Fix numerous minor issues with incorrectly tags on enumerant names and
table titles (public issue 330).
* Generate specversion.txt date in UTC time and RFC 2822 format
(public issue 335).
* Convert link to the SPIR-V Specification for
flink:VkShaderModuleCreateInfo into an internal link to the normative
reference (public issue 336).
* Add ename:VK_ERROR_OUT_OF_MEMORY error code to
flink:vkCreateDebugReportCallbackEXT (public issue 337).
Internal Issues:
* Update style guide regarding use of code:NULL and dname:VK_NULL_HANDLE
(internal issue 393).
* Change the definition of latexmath:[$q$] in the
<<textures-image-level-selection,texture image level selection>> section
to be the index of the maximum defined level for the view, not the
number of levels in the view (internal issue 406).
* Allow developers to override dname:VK_DEFINE_NON_DISPATCHABLE_HANDLE
with their own binary-compatible definition (internal issue 439).
* Fix +vk_platform.h+ conditional logic causing compile failure with some
Android compilers (internal issue 441).
* Implement the single-branch model as described above (internal issue
461).
Other Issues:
Jon Leech