PARTY, MUST, MAY, SHANT

Every regulative rule starts with PARTY, the one the rule applies to, followed by a modal that says whether the action is required, allowed or forbidden.

Syntax

PARTY party MUST action
PARTY party MAY action
PARTY party SHANT action
PARTY party MUST NOT action
PARTY party DO action

The rest of the rule (PROVIDED, WITHIN, HENCE, LEST) is described in Deadlines and consequences.

Example files:

-- PARTY keyword examples (regulative rules for legal contracts)
--
-- This file demonstrates L4's regulative features for legal drafting,
-- showing how to express obligations, permissions, and prohibitions that
-- are commonly found in contracts, legislation, and regulations.

-- Type Declarations

DECLARE `Legal Entity` IS ONE OF
  `The Borrower`
  `The Lender`
  `The Seller`
  `The Buyer`
  `The Employee`
  `The Employer`
  `The Tenant`
  `The Landlord`

DECLARE `Contract Action` IS ONE OF
  `make payment` HAS amount IS A NUMBER
  `deliver goods` HAS description IS A STRING
  `provide services`
  `sign document` HAS `document name` IS A STRING
  `disclose confidential information`
  `vacate premises`
  `pay damages` HAS amount IS A NUMBER

-- Basic Obligation (MUST)

-- Simple payment obligation with a deadline
-- The Borrower must make a payment within 30 days
`payment obligation` MEANS
  PARTY `The Borrower`
  MUST `make payment` 5000
  WITHIN 30

-- Permission (MAY)

-- Early termination right
-- The Tenant may vacate the premises early without penalty
`early termination right` MEANS
  PARTY `The Tenant`
  MAY `vacate premises`
  WITHIN 60

-- Prohibition (SHANT)

-- Non-disclosure obligation (confidentiality clause)
-- The Employee shall not disclose confidential information for 2 years
`confidentiality obligation` MEANS
  PARTY `The Employee`
  SHANT `disclose confidential information`
  WITHIN 730  -- 2 years in days

-- Alternative syntax: MUST NOT
-- Same prohibition expressed differently
`confidentiality obligation alternative` MEANS
  PARTY `The Employee`
  MUST NOT `disclose confidential information`
  WITHIN 730

-- With Consequences (HENCE/LEST)

-- Payment with grace period and penalty
-- If The Borrower pays on time, the contract is fulfilled.
-- If not, they must pay with a penalty within a grace period.
`payment with penalty clause` MEANS
  PARTY `The Borrower`
  MUST `make payment` 1000
  WITHIN 30
  HENCE FULFILLED
  LEST (
    PARTY `The Borrower`
    MUST `make payment` 1100  -- 10% penalty
    WITHIN 15  -- 15-day grace period, counted from when the first deadline is found to have passed
    LEST BREACH
  )

-- Chained Obligations

-- Purchase and delivery contract
-- The Buyer pays, then The Seller must deliver goods
`purchase and delivery contract` MEANS
  PARTY `The Buyer`
  MUST `make payment` 5000
  WITHIN 7
  HENCE
    PARTY `The Seller`
    MUST `deliver goods` "electronic equipment"
    WITHIN 14
    HENCE FULFILLED

-- Service contract with multiple steps
-- Sign document, then provide services, then receive payment
`service agreement` MEANS
  PARTY `The Employee`
  MUST `sign document` "employment contract"
  WITHIN 7
  HENCE
    PARTY `The Employee`
    MUST `provide services`
    WITHIN 90
    HENCE
      PARTY `The Employer`
      MUST `make payment` 3000
      WITHIN 7
      HENCE FULFILLED

-- Testing with #TRACE

-- Test 1: Payment obligation fulfilled on time
#TRACE `payment obligation` AT 0 WITH
  PARTY `The Borrower` DOES `make payment` 5000 AT 20

-- Test 2: Payment obligation breached (no payment before the deadline)
#TRACE `payment obligation` AT 0 WITH
  WAITUNTIL 31

-- Test 3: Early termination right exercised
#TRACE `early termination right` AT 0 WITH
  PARTY `The Tenant` DOES `vacate premises` AT 30

-- Test 4: Confidentiality maintained until the period ends (no breach)
#TRACE `confidentiality obligation` AT 0 WITH
  WAITUNTIL 731

-- Test 5: Payment with penalty - paid in grace period
#TRACE `payment with penalty clause` AT 0 WITH
  WAITUNTIL 31
  PARTY `The Borrower` DOES `make payment` 1100 AT 40

-- Test 6: Purchase and delivery - happy path
#TRACE `purchase and delivery contract` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 5000 AT 5
  PARTY `The Seller` DOES `deliver goods` "electronic equipment" AT 15

-- Test 7: Service agreement - complete workflow
#TRACE `service agreement` AT 0 WITH
  PARTY `The Employee` DOES `sign document` "employment contract" AT 3
  PARTY `The Employee` DOES `provide services` AT 50
  PARTY `The Employer` DOES `make payment` 3000 AT 55

,

-- MUST Keyword Examples - Legal Obligations

-- Type Declarations

DECLARE `Contract Party` IS ONE OF
  `The Borrower`
  `The Lender`
  `The Buyer`
  `The Seller`
  `The Contractor`
  `The Client`
  `The Tenant`
  `The Landlord`

DECLARE `Contract Action` IS ONE OF
  `make payment` HAS `payment amount` IS A NUMBER
  `deliver goods` HAS `goods description` IS A STRING
  `provide services` HAS `service description` IS A STRING
  `sign contract`
  `provide notice` HAS `notice content` IS A STRING
  `complete repairs` HAS `repair description` IS A STRING
  `pay penalty` HAS `penalty amount` IS A NUMBER
  `return security deposit` HAS `deposit amount` IS A NUMBER

-- Basic Payment Obligation

-- Simple payment obligation with a deadline
-- The Borrower must make a payment of $10,000 within 30 days
`monthly loan payment` MEANS
  PARTY `The Borrower`
  MUST `make payment` 10000
  WITHIN 30

-- With HENCE (Consequence on Fulfillment)

-- Purchase contract: If The Buyer pays, then The Seller must deliver
-- This creates a conditional chain of obligations
`purchase and delivery agreement` MEANS
  PARTY `The Buyer`
  MUST `make payment` 25000
  WITHIN 7
  HENCE
    PARTY `The Seller`
    MUST `deliver goods` "industrial machinery"
    WITHIN 14

-- Service contract: After payment, contractor provides services,
-- then client pays the remaining balance
`staged service contract` MEANS
  PARTY `The Client`
  MUST `make payment` 5000  -- Initial deposit
  WITHIN 3
  HENCE
    PARTY `The Contractor`
    MUST `provide services` "website development"
    WITHIN 30
    HENCE
      PARTY `The Client`
      MUST `make payment` 15000  -- Final payment
      WITHIN 7

-- With LEST (Consequence on Breach)

-- Simple breach: If The Borrower doesn't pay, the contract is breached
`payment or breach` MEANS
  PARTY `The Borrower`
  MUST `make payment` 5000
  WITHIN 30
  LEST BREACH

-- Penalty clause: If payment not made on time, a late fee applies
-- with a grace period before final breach
`payment with late fee` MEANS
  PARTY `The Borrower`
  MUST `make payment` 10000
  WITHIN 30
  LEST
    PARTY `The Borrower`
    MUST `make payment` 12000  -- Original amount plus 20% late fee
    WITHIN 15  -- 15-day grace period, counted from when the first deadline is found to have passed
    LEST BREACH

-- Landlord repair obligation: Must repair within deadline,
-- or tenant can deduct repair costs from rent
`landlord repair obligation` MEANS
  PARTY `The Landlord`
  MUST `complete repairs` "fix leaking roof"
  WITHIN 14
  LEST
    PARTY `The Tenant`
    MUST `provide notice` "tenant will arrange repairs and deduct cost"
    WITHIN 3

-- MUST NOT (Prohibition)

-- MUST NOT is equivalent to SHANT - expresses a prohibition
-- The Contractor must not disclose confidential information
-- for 2 years (730 days)
`confidentiality obligation` MEANS
  PARTY `The Contractor`
  MUST NOT `provide notice` "confidential information disclosure"
  WITHIN 730

-- Chained Obligations

-- Complex contract with multiple sequential obligations
-- Demonstrates a complete contract lifecycle
`construction contract workflow` MEANS
  PARTY `The Contractor`
  MUST `sign contract`
  WITHIN 7
  HENCE
    PARTY `The Client`
    MUST `make payment` 50000  -- Down payment
    WITHIN 14
    HENCE
      PARTY `The Contractor`
      MUST `provide services` "foundation work"
      WITHIN 30
      HENCE
        PARTY `The Client`
        MUST `make payment` 150000  -- Final payment
        WITHIN 7

-- Lease agreement with security deposit return
`lease termination and deposit return` MEANS
  PARTY `The Tenant`
  MUST `provide notice` "60-day notice of non-renewal"
  WITHIN 60
  HENCE
    PARTY `The Tenant`
    MUST `complete repairs` "restore premises to original condition"
    WITHIN 30
    HENCE
      PARTY `The Landlord`
      MUST `return security deposit` 3000
      WITHIN 14
      LEST
        PARTY `The Landlord`
        MUST `return security deposit` 3090  -- With 3% interest penalty
        WITHIN 30
        LEST BREACH

-- Testing Obligations

-- Test 1: Basic obligation fulfilled on time
#TRACE `monthly loan payment` AT 0 WITH
  PARTY `The Borrower` DOES `make payment` 10000 AT 20

-- Test 2: Basic obligation breached (no payment made; time passes the deadline)
#TRACE `monthly loan payment` AT 0 WITH
  WAITUNTIL 31

-- Test 3: Conditional obligation - full chain executed
#TRACE `purchase and delivery agreement` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 25000 AT 5
  PARTY `The Seller` DOES `deliver goods` "industrial machinery" AT 15

-- Test 4: Payment with late fee - paid during grace period
#TRACE `payment with late fee` AT 0 WITH
  WAITUNTIL 31
  PARTY `The Borrower` DOES `make payment` 12000 AT 40

-- Test 5: Payment with late fee - breached (no payment at all)
#TRACE `payment with late fee` AT 0 WITH
  WAITUNTIL 31
  WAITUNTIL 50

-- Test 6: Staged service contract - complete workflow
#TRACE `staged service contract` AT 0 WITH
  PARTY `The Client` DOES `make payment` 5000 AT 2
  PARTY `The Contractor` DOES `provide services` "website development" AT 25
  PARTY `The Client` DOES `make payment` 15000 AT 30

-- Test 7: Construction workflow - happy path
#TRACE `construction contract workflow` AT 0 WITH
  PARTY `The Contractor` DOES `sign contract` AT 5
  PARTY `The Client` DOES `make payment` 50000 AT 15
  PARTY `The Contractor` DOES `provide services` "foundation work" AT 40
  PARTY `The Client` DOES `make payment` 150000 AT 45

-- Test 8: Lease termination with deposit return
#TRACE `lease termination and deposit return` AT 0 WITH
  PARTY `The Tenant` DOES `provide notice` "60-day notice of non-renewal" AT 30
  PARTY `The Tenant` DOES `complete repairs` "restore premises to original condition" AT 55
  PARTY `The Landlord` DOES `return security deposit` 3000 AT 65

-- Test 9: Landlord repair obligation - landlord complies
#TRACE `landlord repair obligation` AT 0 WITH
  PARTY `The Landlord` DOES `complete repairs` "fix leaking roof" AT 10

-- Test 10: Landlord repair obligation - landlord misses the deadline, so the tenant must notify
#TRACE `landlord repair obligation` AT 0 WITH
  WAITUNTIL 15

,

-- MAY Keyword Examples - Permissions and Options in Contracts
--
-- The MAY keyword expresses permissions, rights, and options - actions that a
-- party is permitted (but not required) to perform. Unlike MUST (obligation),
-- MAY creates no duty, and failure to exercise a MAY right is not a breach.
--
-- Key Concepts:
--   • MAY creates a permission or option to perform an action
--   • WITHIN specifies the time period during which the option can be exercised
--   • HENCE specifies what follows, whether or not the option is exercised:
--     when the deadline passes without it, the rule also continues with HENCE
--   • Unlike MUST, not exercising a MAY option is never a breach
--
-- Common Legal Uses:
--   • Early termination rights (lease agreements, employment contracts)
--   • Extension options (option to renew, extend deadlines)
--   • Prepayment rights (loan agreements)
--   • Redemption rights (securities, convertible notes)
--   • Put/call options (shareholder agreements)
--   • Rights of first refusal
--
-- This file demonstrates typical permission patterns found in:
--   • Commercial contracts
--   • Lease agreements
--   • Loan agreements
--   • Employment contracts
--   • Shareholder agreements
--

-- Type Declarations

DECLARE `Contract Party` IS ONE OF
  `The Lender`
  `The Borrower`
  `The Tenant`
  `The Landlord`
  `The Investor`
  `The Company`
  `The Buyer`
  `The Seller`

DECLARE `Contract Action` IS ONE OF
  `prepay loan` HAS `prepayment amount` IS A NUMBER
  `extend lease` HAS `extension months` IS A NUMBER
  `claim warranty benefit` HAS `benefit description` IS A STRING
  `convert to equity` HAS `conversion amount` IS A NUMBER
  `exercise put option` HAS `share quantity` IS A NUMBER
  `terminate early`
  `demand acceleration`
  `make payment` HAS `payment amount` IS A NUMBER

-- Basic Permission (Prepayment Right)

-- Simple prepayment right in a loan agreement
-- The Borrower may prepay the loan in full within the first year without penalty
`prepayment option` MEANS
  PARTY `The Borrower`
  MAY `prepay loan` 100000
  WITHIN 365

-- Permission After Obligation (Warranty Claim)

-- Purchase contract: After payment, buyer may claim warranty benefits
-- This is common in consumer protection and sale of goods contracts
`purchase with warranty` MEANS
  PARTY `The Buyer`
  MUST `make payment` 5000
  WITHIN 7
  HENCE
    PARTY `The Buyer`
    MAY `claim warranty benefit` "extended warranty coverage"
    WITHIN 365

-- Renewable Option (Lease Extension)

-- Lease renewal option: If tenant extends once, they get another option
-- Common in commercial real estate leases
`first renewal option` MEANS
  PARTY `The Tenant`
  MAY `extend lease` 12  -- First 12-month extension
  WITHIN 60  -- Must notify 60 days before expiry
  HENCE
    PARTY `The Tenant`
    MAY `extend lease` 12  -- Second 12-month extension available
    WITHIN 60

-- Remedial Permission (Acceleration Clause)

-- If borrower breaches, lender may demand full repayment immediately
-- Standard clause in loan agreements to protect lender
`payment with acceleration right` MEANS
  PARTY `The Borrower`
  MUST `make payment` 10000
  WITHIN 30
  LEST
    PARTY `The Lender`
    MAY `demand acceleration`  -- Full loan becomes due immediately
    WITHIN 14

-- Convertible Note Option

-- Investor may convert their note to equity at any time
-- Common in startup financing and convertible instruments
`conversion option` MEANS
  PARTY `The Investor`
  MAY `convert to equity` 500000
  WITHIN 730  -- 2-year window

-- Put Option (Shareholder Agreement)

-- Shareholder may require the company to buy back shares
-- Common in private company shareholder agreements
`shareholder put option` MEANS
  PARTY `The Investor`
  MAY `exercise put option` 100000  -- 100,000 shares
  WITHIN 1825  -- 5-year window

-- Early Termination Right

-- Tenant may terminate lease early with notice
-- Common in residential and commercial leases
`early termination clause` MEANS
  PARTY `The Tenant`
  MAY `terminate early`
  WITHIN 180  -- Can terminate within first 6 months
  HENCE FULFILLED  -- exercised or not, nothing further follows

-- Chained Permissions

-- After payment, buyer may claim warranty; if claimed, seller must service
-- Demonstrates how permissions can trigger subsequent obligations
`warranty claim process` MEANS
  PARTY `The Buyer`
  MUST `make payment` 25000
  WITHIN 14
  HENCE
    PARTY `The Buyer`
    MAY `claim warranty benefit` "defect repair"
    WITHIN 730  -- 2-year warranty period
    HENCE
      PARTY `The Seller`
      MUST `make payment` 5000  -- Seller must cover repair costs
      WITHIN 30

-- Testing Permissions

-- Test 1: Prepayment option exercised
#TRACE `prepayment option` AT 0 WITH
  PARTY `The Borrower` DOES `prepay loan` 100000 AT 180

-- Test 2: Prepayment option not exercised before the deadline (valid - no breach)
#TRACE `prepayment option` AT 0 WITH
  WAITUNTIL 366

-- Test 3: Purchase with warranty - full path
#TRACE `purchase with warranty` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 5000 AT 5
  PARTY `The Buyer` DOES `claim warranty benefit` "extended warranty coverage" AT 100

-- Test 4: Purchase with warranty - payment but no claim
#TRACE `purchase with warranty` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 5000 AT 5

-- Test 5: Lease renewal - first extension exercised
#TRACE `first renewal option` AT 0 WITH
  PARTY `The Tenant` DOES `extend lease` 12 AT 30

-- Test 6: Lease renewal - both extensions exercised
#TRACE `first renewal option` AT 0 WITH
  PARTY `The Tenant` DOES `extend lease` 12 AT 30
  PARTY `The Tenant` DOES `extend lease` 12 AT 90

-- Test 7: Acceleration right triggered by breach
#TRACE `payment with acceleration right` AT 0 WITH
  WAITUNTIL 31
  PARTY `The Lender` DOES `demand acceleration` AT 35

-- Test 8: Acceleration right not needed (payment made)
#TRACE `payment with acceleration right` AT 0 WITH
  PARTY `The Borrower` DOES `make payment` 10000 AT 20

-- Test 9: Conversion option exercised
#TRACE `conversion option` AT 0 WITH
  PARTY `The Investor` DOES `convert to equity` 500000 AT 365

-- Test 10: Put option exercised
#TRACE `shareholder put option` AT 0 WITH
  PARTY `The Investor` DOES `exercise put option` 100000 AT 1000

-- Test 11: Early termination exercised
#TRACE `early termination clause` AT 0 WITH
  PARTY `The Tenant` DOES `terminate early` AT 90

-- Test 12: Early termination not exercised before the deadline
#TRACE `early termination clause` AT 0 WITH
  WAITUNTIL 181

-- Test 13: Warranty claim process - complete workflow
#TRACE `warranty claim process` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 25000 AT 7
  PARTY `The Buyer` DOES `claim warranty benefit` "defect repair" AT 200
  PARTY `The Seller` DOES `make payment` 5000 AT 220

,

-- SHANT Keyword Examples - Legal Prohibitions
--
-- The SHANT keyword (and its alternative MUST NOT) expresses legal prohibitions
-- - actions that a party is forbidden from performing.
--
-- Key Concepts:
--   • SHANT means "shall not" - a party must refrain from an action
--   • If the prohibited action occurs, it results in BREACH
--   • SHANT and MUST NOT are equivalent - use whichever reads more naturally
--   • Prohibitions are maintained by NOT performing the forbidden action
--
-- Common Legal Uses:
--   • Non-disclosure agreements (protecting confidential information)
--   • Non-compete clauses (restricting competitive activities)
--   • Lease restrictions (limiting tenant actions)
--   • Loan covenants (preventing risky borrower behavior)
--
-- This file demonstrates typical prohibition patterns found in:
--   • Employment contracts
--   • Lease agreements  
--   • Loan agreements
--   • Commercial contracts
--

-- Type Declarations

DECLARE `Legal Party` IS ONE OF
  `The Employee`
  `The Employer`
  `The Tenant`
  `The Landlord`
  `The Borrower`
  `The Lender`

DECLARE `Prohibited Action` IS ONE OF
  `disclose confidential information`
  `compete with employer` HAS `competing business` IS A STRING
  `sublease the premises`
  `make alterations` HAS `alteration type` IS A STRING
  `incur additional debt` HAS `debt amount` IS A NUMBER
  `dispose of collateral`
  `pay penalty` HAS `penalty amount` IS A NUMBER

-- Basic Prohibition - Non-Disclosure Agreement

-- A simple prohibition with a time period
`confidentiality obligation` MEANS
  PARTY `The Employee`
  SHANT `disclose confidential information`
  WITHIN 1825  -- 5 years in days

-- Prohibition with MUST NOT (Alternative Syntax)

-- MUST NOT and SHANT are equivalent ways to express prohibition
`non-compete clause` MEANS
  PARTY `The Employee`
  MUST NOT `compete with employer` "software development"
  WITHIN 730  -- 2 years in days

-- Prohibition with Breach Consequence

-- If the prohibition is violated, an explicit breach is declared
`no subleasing` MEANS
  PARTY `The Tenant`
  SHANT `sublease the premises`
  WITHIN 365
  LEST BREACH BY `The Tenant` BECAUSE "violated lease agreement section 8"

-- Conditional Prohibition

-- Prohibition applies only when a condition is met
`structural alteration prohibition` MEANS
  PARTY `The Tenant`
  SHANT `make alterations` `alt type` PROVIDED
    `alt type` EQUALS "structural" OR `alt type` EQUALS "load-bearing"
  WITHIN 365
  LEST BREACH BY `The Tenant` BECAUSE "made unauthorized structural changes"

-- Prohibition with Financial Threshold

-- Common in loan agreements - borrower cannot take on significant new debt
`debt restriction` MEANS
  PARTY `The Borrower`
  SHANT `incur additional debt` `new debt` PROVIDED `new debt` GREATER THAN 50000
  WITHIN 1095  -- 3 years
  LEST BREACH BY `The Borrower` BECAUSE "exceeded debt covenant limit"

-- Prohibition with Financial Penalty

-- If prohibition is violated, a financial penalty must be paid
`collateral protection` MEANS
  PARTY `The Borrower`
  SHANT `dispose of collateral`
  WITHIN 1095
  LEST
    PARTY `The Borrower`
    MUST `pay penalty` 10000
    WITHIN 30
    LEST BREACH BY `The Borrower` BECAUSE "failed to pay penalty for collateral disposal"

-- Testing Prohibitions

-- Test 1: Prohibition complied with (no action taken until the period ends - this is success)
#TRACE `confidentiality obligation` AT 0 WITH
  WAITUNTIL 1826

-- Test 2: Prohibition violated (action taken - this should result in breach)
#TRACE `confidentiality obligation` AT 0 WITH
  PARTY `The Employee` DOES `disclose confidential information` AT 100

-- Test 3: Conditional prohibition not violated (condition not met; the prohibition stays in force)
#TRACE `structural alteration prohibition` AT 0 WITH
  PARTY `The Tenant` DOES `make alterations` "cosmetic" AT 50

-- Test 4: Conditional prohibition violated (condition met)
#TRACE `structural alteration prohibition` AT 0 WITH
  PARTY `The Tenant` DOES `make alterations` "structural" AT 50

-- Test 5: Financial prohibition within threshold (allowed; the prohibition stays in force)
#TRACE `debt restriction` AT 0 WITH
  PARTY `The Borrower` DOES `incur additional debt` 40000 AT 100

-- Test 6: Financial prohibition exceeded (breach)
#TRACE `debt restriction` AT 0 WITH
  PARTY `The Borrower` DOES `incur additional debt` 75000 AT 100

PARTY

PARTY names who the rule applies to: a value of the rule's party type, usually a value of an enumeration. Only an event by that party can fulfil or breach the rule; an event by anyone else is skipped.

DECLARE Party IS ONE OF `The Borrower`, `The Lender`
DECLARE Action IS ONE OF
  `prepay loan`
  `make payment` HAS amount IS A NUMBER

GIVETH A DEONTIC Party Action
`payment obligation` MEANS
  PARTY `The Borrower`
  MUST `make payment` 5000
  WITHIN 30

The party and action types are the two parameters of the rule's type, DEONTIC Party Action; see DEONTIC. The action is a value of the action type, matched as a pattern: `make payment` 5000 matches only a payment of 5000. A plain name in the action matches anything: `make payment` amount matches a payment of any amount, even when amount or price is already defined. To match the value of a name, write `make payment` (EXACTLY price); see EXACTLY.

MUST

MUST is an obligation: the party is required to take the action before the deadline.

• Taken in time: the rule continues with HENCE (by default FULFILLED).
• Not taken when the deadline passes: the rule continues with LEST (by default BREACH).

DECLARE Party IS ONE OF Seller, Buyer
DECLARE Action IS ONE OF `deliver goods`

GIVETH A DEONTIC Party Action
`delivery` MEANS
  PARTY Seller
  MUST `deliver goods`
  WITHIN 14
  HENCE FULFILLED
  LEST BREACH BY Seller

#TRACE `delivery` AT 0 WITH
  PARTY Seller DOES `deliver goods` AT 10

MAY

MAY is a permission: the party is allowed, but not required, to take the action. Typical uses are rights to terminate early, renew, prepay or convert.

• Taken in time: the rule continues with HENCE (by default FULFILLED).
• Not taken when the deadline passes: the rule also continues with HENCE. Not using a permission is never a breach, and a LEST after MAY is not used.

DECLARE Party IS ONE OF `The Borrower`
DECLARE Action IS ONE OF `prepay loan` HAS amount IS A NUMBER

GIVETH A DEONTIC Party Action
`prepayment option` MEANS
  PARTY `The Borrower`
  MAY `prepay loan` 100000
  WITHIN 365

A MAY is often the step after an obligation, under its HENCE, or leads to an obligation of another party under its own HENCE. If not using the permission should have a consequence, write the rule with MUST or DO and a LEST instead.

SHANT and MUST NOT

SHANT is a prohibition: the party must not take the action during the period. MUST NOT means exactly the same; use whichever reads closer to the source text.

• Taken: the rule continues with LEST (by default BREACH).
• Not taken when the deadline passes: the rule continues with HENCE (by default FULFILLED).

DECLARE Party IS ONE OF `The Employee`
DECLARE Action IS ONE OF `disclose confidential information`

GIVETH A DEONTIC Party Action
`confidentiality` MEANS
  PARTY `The Employee`
  SHANT `disclose confidential information`
  WITHIN 730
  LEST BREACH BY `The Employee` BECAUSE "breach of confidentiality"

GIVETH A DEONTIC Party Action
`confidentiality, worded as MUST NOT` MEANS
  PARTY `The Employee`
  MUST NOT `disclose confidential information`
  WITHIN 730

DO

DO names an action that is neither required nor forbidden. It is meant for rules that give both HENCE and LEST; when they are left out, it behaves like MUST.

Summary

Modal	Meaning	Action taken in time	Deadline passes without the action
MUST	obligation	HENCE	LEST (default BREACH)
MAY	permission	HENCE	HENCE
SHANT / MUST NOT	prohibition	LEST (default BREACH)	HENCE
DO	bare action	HENCE	LEST (default BREACH)

Related pages

• Regulative rules: the parts of a rule and how to test it
• Deadlines and consequences: WITHIN, HENCE, LEST, PROVIDED, EXACTLY, RAND, ROR
• BECAUSE: reasons for a breach