UML-2.5.1

SysMLv1: TIP: SysMLv1: Cameo: JoinNode and MergeNode distinguishing notations option

UML/SysMLv1: ISSUE: Cameo Simulation Toolkit (v2024x): Simulation does not test even the simplest broken OCL2.0 Constraint. The unsatisfactory "WORKAROUND" is to use another language for the Constraint (they nearly all work).

SysMLv1: Webel strongly recommends a looser, more "logical" modelling strategy over modelling practices with strong coupling to "physical" ownership. Many of the Webel Best Practices support this approach.

SysMLv1: A 'part property' in SysMLv1 does not formally include 'port' (which is considered a special kind of property), even though the Port metaclass in UML2 extends Property and a 'port' may have 'composite' aggregation and be typed by a Block.

UML2/SysMLv1: A control Pin (a Pin with isControl = True) for a CallBehaviorAction does not have a corresponding Parameter

Webel: SysML4Mathematica: A custom stereotype «M:Paclet» applied to a SysML Package denotes a Wolfram Package Paclet. An «M:Package» is a specialisation of SysMLv1 Block and denotes a Wolfram Language Package.

Webel: SysML4Mathematica: A SysML/UML Usage (keyword «uses») is used to indicate a Wolfram Package Needs import, where an «M:Package» is a specialisation of Block (not a SysML/UML Package) and denotes a Wolfram Language Package.

Webel: SysML4Mathematica: Activity Diagrams used purely for analysis and as development aids are not required to show every ControlFlow, may omit InitialNode and ActivityFinalNode, and are not required to fully validate in SysML tools or execute.

Webel: SysML4Mathematica: An OptionsPattern[] may be represented by an «M:OptionsPattern» SysMLv1 Block with «M:Opt» properties. An «M:Opt» property represents an Options[] Rule IMPLICITLY (an «M:Opt» does not use the Rule block modelling recipe).

Mathematica: CONVENTION: A prefix 'eq$' indicates a symbolic equation (typically using 'sym$' human-friendly markup "symbols")

Webel: SysML/MBSE: Suggest don't fuss about ownership (containment) too much early on. Focus on "logical" modelling, values, flows, relationships between elements. Suggest perform regular separate modelling "housekeeping" sweeps to deal with ownership.

SysMLv1: Webel often uses Model packages for most modelling and reserves Package for code-like elements, OpaqueBehavior sub-libraries, instances, and elements reverse-engineered from code. But there are no hard and fast rules about Package vs Model.

Webel: SysML: If you are working within a self-contained model you may freely include diagrams icons for navigation and model elements from other Packages in a Package Diagram or "focus" BDD but beware of breaking Shared Package and library dependencies!

ISSUE: Cameo Simulation Toolkit: v2024x: Although does not respect inheritance of attributes of Signals on SendSignalAction or un-marshalling AcceptEventAction DOES require them on 'effect' Behaviors.

SysMLv1: Cameo Simulation Toolkit: GOTCHA: Do not use Associations with Signal attributes, they will become null when fed as argument values for Parameters of 'effect' Behaviors of Transitions

SysMLv1/UML2: Although fUML does not support InterruptibleActivityRegion, Cameo Simulation Toolkit does support InterruptibleActivityRegion

SysMLv1.7/fUMLv1.4: Cameo Simulation Toolkit v2024x: Using an extending Enumeration literal as a parameter argument value runs but a WARN is issued.

ISSUE: Cameo Simulation Toolkit: v2024x: Does not show argument Pins corresponding to inherited attributes of Signal on SendSignalAction or an un-marshalling AcceptEventAction. No known UML2.5.1 or fUML-1.4 constraint; no obvious tool display option.

Cameo Simulation Toolkit includes a (basic) TimeEvent, but fUML-1.3/1.4 does not. There are many different supported time units for duration constraints, and you can also use property values in durations.

TIP: SysMLv1/UML: Cameo Simulation Toolkit: HOWTO convert an fUML ReadLine CLI String to a Boolean for cleaner DecisionNode tests against a LiteralBoolean [true] guard.

TIP/GOTCHA: SysMLv1/fUML: Cameo Simulation Toolkit: If you have a ControlFlow loop with a DecisionNode test you MUST have a MergeNode for the continuation path ControlFlow (typically entered also from an InitialNode or other loop starting point).

TIP/GOTCHA: SysMLv1/UML: Cameo Simulation Toolkit: If you use a «decisionInputFlow» to a DecisionNode you MUST also have a ControlFlow to the DecisionNode; if you don't use an explicit «decisionInputFlow» you don't need the "extra" ControlFlow

Dr Darren says: 'You can't obtain the optimum benefit of graphical engineering with SysML without becoming mindful of the cognitive and artistic aspects of graphical modelling. The "Zen of SysML" matters!' Just like an elegant electronics device design.

The Webel recipe for pragramatic SE with SysML omits many of the concerns addressed by fully-fledged systems engineering frameworks. Many of these can be partially addressed by using custom Stereotypes for extraction using query view tables.

Webel: SysML: SE: The custom stereotype keyword «design» covers elements involved with BOTH design and/or implementation aspects in the 'solution' zone. (In more comprehensive SE methodologies design and implementation are often treated separately.)

Webel: SysML: SE: Naming convention: '0' used for a Package/Model name indicates a zone dedicated to a formal systems engineering breakdown (functional analysis, blackbox, whitebox, logical vs design or implementation etc.)

Webel: SysMLv1: TIP: Use semantically meaningful Association names and/or custom Stereotypes where applicable. They can also often be used as pseudo OWL/RDF semantic triples. But don't use Association names where an ItemFlow can capture an exchange item!

Webel: SysML: Heard of "follow the money"? In MBSE we "follow the flows"! Identify requests, data packets, messages, signals early on and use ItemFlow as often as you can wherever you can! Adopt a signal processing mindset throughout (systems thinking).

Webel: SysML/UML: Dr Darren explains HOWTO use concise 'i'/'o' (input/output) Pin and Parameter naming conventions to promote a signal processing mindset in Activity Diagrams. And HOWTO get them compact.

Webel: SysMLv1: Dr Darren for LinkedIn: On "Trusting The Type" and avoiding unnecessary verbose repetitive Property names ... unless you really, really need them and really do have reasons to use them, and then only use concise role indicators anyway!

TIP: SysMLv1: MagicDraw/Cameo: Activity Diagrams: Consider using the Pin display mode 'Name And Type Labels Inside' for 'Position of Labels'. Dr Darren swears by it!

TIP: UML/SysML: MagicDraw/Cameo: Activity Diagrams: Pins: You can display the 'multiplicity' of the underlying Parameter on Pins symbols using Edit Compartments. (The 'multiplicity' shows anyway if the :Type is shown.)

TIP: UML/SysML: MagicDraw/Cameo: Activity Diagrams: ActivityParameterNodes: Displaying the underlying 'parameter::multiplicity' using Edit Compartments is extremely useful!

UML/SysML: MagicDraw/Cameo: Edit Compartments: ActivityParameterNode: Can't select the 'parameter::multiplicity'? Run the synchronisation between the Activity in the direction Synchronize Activity Parameter Nodes by Activity Parameter then try again!

Webel: Psy/MPsy: Psychrometrics for Mathematica: '$HC' in a function name indicates pure sensible heating or cooling (with no change in water vapour content). Such functions may also be used in the pure sensible portion of a 2-step treatment.

Webel: Mathematica: CONVENTION: A prefix '$doc' indicates a documentation String for each primary variable/quantity (argument or output)

Webel: Mathematica: CONVENTION: A prefix 'sym$' indicates a markup variable "symbol" for a documented variable. It need not be a String, but each referenced part MUST be a String - not a Mathematica Symbol - to avoid namespace clashes!

Webel: SysML4Mathematica: Does every bit of the Mathematica code need to be modelled in SysML? No. Typically just the main function parameters and their interdependencies, data structures, and main code logic. Except for special or educational purposes.

Webel: SysML/UML: Some example diagrams show extremely fine-grained and trivial examples purely for educational and capability demonstration purposes (not as practical recommendations for real-world projects). You can sometimes just use code in SysML.

Webel: SysML4Mathematica: POLICY: Handle flow sign changes via a single negative (not duplicated and "adjusted" algebra). This strategy may come at a very slight performance cost (for benefit of more robustness).

Webel: SysML4Mathematica: SysML Activities and SysML Activity Diagrams CAN represent some functional programming paradigms (sort of). You can type Parameters by encapsulations of functions and pass them to/from InputPins/OutputPins of Actions.

Webel: SysML4Mathematica: TIP: Representing Mathematica Paclets and their inter-dependencies as SysML Packages modelled in SysML Package Diagrams can really help you organise your Wolfram Language code on complex projects!

Webel: SysML4Mathematica: TIP: Representing Mathematica functions as SysML ConstraintBlocks modelled in Block Definition Diagram (BDD) overviews can really help you organise and document your Wolfram Language code on complex projects!

Webel: SysML4Mathematica: TIP: Representing Mathematica functions as SysML ConstraintBlocks modelled in SysML Parametric Diagrams and as Activities in SysML Activity Diagrams is super for analysing the dependencies between functions and their arguments!

Webel: SysML4Mathematica: TIP: Exported SysML Diagrams can be embedded in Mathematica Notebooks!

Webel: SysML4Mathematica: An Association used as the Type of an argument or return is represented by a Block '<||>'. A List used as as the Type of an argument or return is represented by a Block '{}'. (Extending types may adapt the notation.)

SysML/UML: MagicDraw/Cameo: GOTCHA: Connecting a typed OutputPin to an untyped (UNSPECIFIED) InputPin with an ObjectFlow changes the type of the InputPin

Webel: SysML4Mathematica: Convention: A '$E' in a function name indicates that all parameters (arguments and return) are Mathematica '_' expressions. However, when representing such functions as Activities they may end up getting strongly typed in tools!

Webel: SysML4Mathematica: When modelling the main logic flow of Mathematica code with Activity Diagrams it isn't necessary to model every Mathematica construct. Placeholder Actions, OpaqueActions , and OpaqueBehaviors (as CallBehaviorActions) may be used.

SysML/UML: MagicDraw/Cameo: To display the body of an OpaqueBehavior on a usage (CallBehaviorAction) in an Activity Diagram use an element property callout of 'Body' into a Note with a handle to the CallBehaviorAction

Webel: SysML4Mathematica: An '@' prefix in the name of a Block indicates a data structure (such as an Association or List) that does not have a corresponding MTools class or a Webel Abstract Data Type (ADT) "pseudo class" in the Wolfram Language code.

Webel: SysML4Mathematica: An '@' prefix in the name of a ConstraintBlock, Activity, or OpaqueBehavior indicates that it is a "@pseudo" function not represented directly in the Wolfram Language or Webel code libraries (typically for minor maths or logic)

ISSUE: MagicDraw/Cameo: v2022x Golden, v2022xRefresh1: Comment can't connect anchor to another Comment as annotatedElement

[FIXED in v2022Refresh1]: BUG: MagicDraw/Cameo: 19SP3/v2022xGolden: Activity Diagrams: Pin display mode 'Position of Labels' does not stick, label positions in Diagrams have sometimes moved after re-opening a project [and "FIX"]

On the Webel Best Practice modelling tips for SysML (and UML). If you want to model the Webel way, use them, if you don't, ignore them. They are ONLY offered as options and graphical modelling paradigms and idioms for you to consider.

Webel: On going beyond SysML (and UML) with additional modelling practices, policies, and additional semantics

Dr Darren explains: Why I am not offering SysML diagrams on some of my LinkedIn TIP postings

MagicDraw/Cameo: UML/SysML: TIP: Activity Diagrams: Learn how to use the Refactor > Extract feature to divide-and-conquer and identify cleaner flow and logic. Get control of those crossed wires!

Webel: MagicDraw/Cameo: UML/SysML: TIP: Activity Diagrams, StateMachine Diagrams, and port-based IBDs: Keep it loose initially with oblique (no break) paths, then square it up with rectangular paths at the very end

UML/SysML: TIP: Using Cameo Simulation Toolkit will strengthen your use of Activity Diagrams even when they are "just" analysis diagrams

MagicDraw/Cameo: 2022xGolden: TIP/GOTCHA: Mac: HOWTO Load the available plugins in the Resource/Plugin Manager

Cameo Simulation Toolkit: v19SP3: GOTCHA/BUG: When a Property is typed by an abstract Block an instance of a concrete specialising Block (where available) will automatically be created and assigned even when the lower multiplicity is 0

MagicDraw/Cameo 19SP3/v2022xGolden: [FIXED in v2022xRefresh1]: Activity Diagrams: Pin display mode 'Position of Labels' does not work correctly for 'Name And Type Labels Inside', only shows the Name inside (not the Label) [and WORKAROUND]

Cameo Simulation Toolkit: You can assign the results of simulations calculations on instances to the default values of properties of the Classes/Blocks that type the instance.

UML/SysML: MagicDraw/Cameo: 19SP3: Instance Table Diagram sometimes does not display the values for nested value properties

UML/SysML: MagicDraw/Cameo: Instance Table Diagrams are one of the most powerful features of MagicDraw/Cameo! Learn to use them to progressively test, debug, and evolve your models as you work!

UML/SysML: MagicDraw/Cameo 19SP3: GOTCHA/TIP: An Instance Table will not display a row for instances typed by an abstract Class/Block (although one can show such instances as InstanceSpecification symbols on a Class Diagram or Block Definition Diagram)

UML/SysML: Cameo Simulation Toolkit 19SP3: GOTCHA/TIP: ConstraintBlock constraints: Not every available constraint language can handle Enumeration literals (if in doubt choose 'English')

UML: Cameo Simulation Toolkit 19SP3: GOTCHA: CreateObjectAction ignores an Artifact as 'classifier' even though Artifact is a Classifier

GOTCHA: UML/SysML: Cameo Simulation Toolkit 19SP3: A [true] or [false] guard on an ActivityEdge MUST be a LiteralBoolean, not just characters typed in, or the evaluation may give unexpected or ill-defined results

UML/SysML: Cameo Simulation Toolkit 19SP3: A parent Activity with a DecisionNode that uses a Activity as a decisionInput Behavior terminates immediately after the decisionInput terminates (but OpaqueBehavior works)

UML/SysML: Cameo Simulation Toolkit 19SP3: GOTCHA: Will not evaluate a guard using a token from a decisionInputFlow UNLESS a decisionInput Behaviour is explicitly defined (but Alf does)

MagicDraw/Cameo: Rule: Internal Block Diagram and Block structure compartment: only one symbol for a given Property may be shown.

MagicDraw/Cameo: Display option: You can choose whether to show Domain Specific Language (DSL) stereotypes: 'None', 'All', 'Only Last'

Webel Parsing Analysis: MagicDraw/Cameo: SysML1.6+: ElementGroup-based Snippets do not list in the compartment of Package/Model symbols because ElementGroup is based on the UML Comment, which does not list in Package/Model symbols.

UML/SysML: MagicDraw/Cameo: WARNING: If you assign a value to a Slot for an untyped Property then assign a ValueType later it will DELETE your assigned value! Assign a type first .

UML2/SysML1.x: Property: derived vs derived union vs subsetted

Webel Parsing Analysis: It does not matter whether you use a Package or a Model package. (The informal Webel convention is that Models are used for systems engineering analysis with SysML and Packages are reserved for code-related software engineering.)

Webel Parsing Analysis: A stereotype with keyword «pa:from» may be applied to a Dependency from a Package to another Package within the Source Input Zone to indicate that all of its Elements were directly or indirectly elicited from source Documents.

MagicDraw/Cameo v19SP3: UML/SysML: HOWTO Set an OpaqueExpression on a Slot that seems to be stuck on a numerical value.

Webel Parsing Analysis: The absolute basics of the process (SysMLv1.x form)

SysMLv2: On the v2 Comment extension of the v2 AnnotatingElement as a candidate Parsing Analysis Container

SysMLv1.x: Q: Why can't a Package with PackageImports be used as a Parsing Analysis text container? Why is the SysML1.6 ElementGroup (extended and customised as the Webel «snippet») far better suited for text-driven model element elicitation?

MagicDraw/Cameo: GOTCHA: When applying a numerical default to a value property make sure the value property has already been typed by Real or Integer (or a ValueType that extends one of them) otherwise it will assign a LiteralString as default.

UML/SysML: In Internal Block Diagrams: If you have a Port with a name that indicates a unique role AND and if there is an ItemFlow on a Connector that implies or suggests the Type of the Port, consider hiding the Type on the Port symbol.

SysML: The placement of usages of Blocks, their Ports, and Connectors in an Internal Block Diagrams DOES NOT necessarily represent physical geometry!

Webel: Cameo Simulation Toolkit v19SP3/v2024x: Could not get ReclassifyObjectAction to work (yet)

In the Webel terminology for a basic control loop there is an 'aim' value (controlled via an actuator) and a 'got' value (a value read from a sensor). The 'got' value is NOT necessarily exactly the same as the actual physical value.

GOTCHA: MagicDraw SysML/Cameo 19SP3: Export to Modelica: The name of a redefining Property must be exactly the same as the Property it redefines or it will not export properly!

Webel: SysML: DO NOT sacrifice modelling naming conventions for the mere sake of carrying organisation-specific names! Instead use tagged values of custom stereotypes as metadata to carry alternative names in parallel with systematic model element names.

MagicDraw/Cameo: If you drag a Behavior from the model browser onto the SYMBOL of a State (that does not already own the Behavior) and set it as an 'entry', 'doActivity', or 'exit' Behavior a "wrapper" Behavior owned by the State will be created.

MagicDraw SysML/Cameo 19SP3: GOTCHA: If you drag a Behavior from the model browser onto the 'entry', 'doActivity', or 'exit' field in a specification dialog of a State it WILL BECOME OWNED by the State (which "steals ownership")!

MagicDraw/Cameo: Display options: On an 'entry', 'doActivity', or 'exit' Behavior of a State you may choose to display the specification code of an OpaqueBehavior or just its name.

Sample problems and example diagrams in graphical language specifications are NOT necessarily indications of how one should model on a real-world project! They often just serve to demonstrate a particular aspect of the specified language.

SysML: When using Property::defaultValue and Property::redefinedValue to carry a "shadow hierarchy" of redefinitions across an entire system hierarchy, considering using a user-defined keyword such as «configuration» or «scenario» on each redefining Block

Webel: UML/SysML: Navigation: ALWAYS offer a way out of a diagram (usually up a hierarchy, but possibly across) using a navigable symbol (linked to a diagram) and/or a diagram symbol. Avoid "cul-de-sacs"! [But beware of shared package cross-dependencies]

MagicDraw/Cameo: v19SP3: Property created by dragging onto a Class or Block a symbol of a Classifier named with a single letter capital name 'N' has a poor name 'N:N'

MagicDraw/Cameo: You can drag a Class symbol onto a Class symbol (in a Class Diagram) or a Block symbol or ValueType symbol onto or Block symbol (in a Block Definition Diagram) to create a new part property or value property

MagicDraw/Cameo: You can drag out a Property (or Port) from a Class or Block symbol to create an Association with the Property (or Port) as one end

GOTCHA: MagicDraw SysML/Cameo 19SP3: Export to Modelica: 'entry', 'doActivity', or 'exit' Behaviors of a State must be directly owned (not just "wrapped") or they won't be seen on export!

UML/SysML: A Boolean "state flag" attribute corresponding to a State can be useful for indicating states in some diagram types (but must be synchronised with Transitions to States carefully).

CAVEAT: The UML-2.5.1 InstanceSpecification does not support Ports!

UML/SysML: During modelling it can really help to create little instance (object) diagrams as you go! This can also help communicate with non-SysML stakeholders.

UML/SysML: If you have a Boolean "state flag" attribute corresponding to a State you MUST set it on an 'entry' of the State, not on the 'effect' of a Transition into the State (otherwise with multiple incoming Transitions it could be WET and breaks SSoT).

UML/SysML: When you use an AddStructuralFeatureValueAction to set one end of a bi-directional Association it also sets the other end.

Cameo Simulation Toolkit matches the Parameters of an effect Behavior and a trigger Operation on a Transition under the hood.

Cameo Simulation Toolkit: GOTCHA: In the Variable pane reference properties are hidden by default (show them using the Options pulldown menu)

BUG: Cameo Simulation Toolkit 19SP3: StateMachine: Crashes with an irrelevant "memory error" report if you fire a signal Trigger during execution of an 'entry' Activity with a timer

UML/SysML: When sending a Signal (message) via a Port the 'target' is the owner of the Port through which the message will be sent, it is NOT the final recipient! So the 'target' is essentially the "sender"!

Cameo: UML: When sending a Signal via a Port with a SendSignalAction, Cameo does not care whether the Port is conjugated (even if it should).

One of the most important reasons to use a Port to send a Signal is that only the connection context, not the sender, knows the ultimate recipient (at the end of a specific Connector).

Webel: SysMLv1: MagicDraw/Cameo: AVOID the "default" SysML Item Flow Creation Mode 'Between Part Types' completely. Use 'Direct' mode, change it as soon as you start any SysML project under Options → Project → General → SysML [Helps prevent a clash/issue]

Cameo/MagicDraw: The Classifier specification setting 'isAbstract' is (for reasons that beggar belief or engineering reason) not by default visible in the Element specification dialog. Enable expertise level 'All' (and for always everwhere).

Webel: MagicDraw/Cameo: Set EVERY element properties & symbol properties filter to 'All' (yes, not just 'Expert', to 'All', even if you are a "novice" on your first project) in EVERY dialog and every project option setting. Use the search filters!

ALL Model-Based Engineering: Just because you can't see a Feature or some other aspect of a SysML (or UML) Element in a tool on a symbol does NOT mean it does not exist in the underlying model (repository)! The model is not just what is DISPLAYED!

Rule #1: A UML or SysML Element in a tool is NOT just an Element symbol in a diagram! A Note is not an Element (compare with a Comment).

UML-2.5.1 refers to 'isTestFirst' in 16.11.3.4 but to isTestedFirst in the attributes list for LoopNode under 16.14.30.4 Attributes

UML-2.5.1: Has an incorrect local Transition with same source and vertex in 'Figure 14.34 Local Transitions'

The entry, doActivity, and effect Behaviors defined on a submachine State are specific that particular usage of its Submachine

Webel: A plain Dependency that is not stereotyped is always strictly timed-ordered; the supplier (target) must exist before the client (source).

The difference between Dependency and Usage in UML is notoriously vague.

MagicDraw/Cameo v19SP3: uses the Block compartment name 'signal receptions' instead of just 'receptions'. [CLAIMED FIXED in v2021x]

In UML and SysML a '/' forward slash prefix before a Property name indicates that it is derived from other elements in the model.

UML/SysML: In Internal Block Diagrams: Consider hiding the name of a named Port or Property in a Diagram if its Type is sufficient to indicate its role.

MagicDraw/Cameo: You can easily find all elements a Stereotype has been applied to using Edit > Find OR via a Generic Table Diagram with the Stereotype as the 'Element type' (with or without sub-types).

The UML multiplicity range notations '0..' and '' are completely equivalent

Webel: SysMLv1/UML: Prefer the Name Display Mode 'both' on CallBehaviorAction symbols (rather than 'Show Action Name', 'Show Behavior Name', or 'Show Both or Behavior Name')

SysMLv1/UML: Prefer owner path indicators over Package containment operators (which are fragile).

Nobody (informed) said that SysML (or even UML) modelling and MBSE is only about graphical modelling, notations, and diagrams! Information can be extracted in many different ways and presented in many different formats from the underlying model!

Webel: SysMLv1/UML: MagicDraw/Cameo: AVOID the the vendor-specific «useCaseModel» stereotype for Model packages, it leads to confusion with the rectangular 'subject' notation

Dependency/Usage relationships in some referenced UML/SysML diagrams on this site are for educational illustration only, they are NOT part of the actual model.

SysML: MagicDraw/Cameo: Diagram Style: Recommend DO NOT use shadows or gradient fill adornments on diagrams! [TIP OFTEN IGNORED]

Webel: SysML symbol colour styles: Recommend use black symbol borders and no symbol fill (or white symbol fill) EXCEPT for special highlighting. Recommend DO NOT use the default VENDOR-SPECIFIC line and fill colours for symbols! [TIP IS MOSTLY IGNORED]

The vendor-specific Action Language Helper (ALH) API can be accessed from all of the various action scripting languages available in MagicDraw, Cameo Systems Modeler, and Cameo Simulation Toolkit

HOWTO set a ValueSpecificationAction to use the * LiteralUnlimitedNatural to drive an 'insertAt' InputPin on an AddStructuralFeatureValueAction in Cameo Simulation Toolkit and Cameo Systems Modeler

Cameo Simulation Toolkit DOES NOT leverage a Reception on a Class/Block at all! Use an AcceptEventAction with a SignalEvent trigger or an 'effect' on a Transition instead. There is a formal fUML restriction that a Reception should not have a method.

Unified Modeling Language 2.5.1

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