I’ve gone through the Weis and Hickman books as well as the Legend of Huma to try and compile a list of what is in the Measure of the Knights of Solamnia, and this is what I’ve found. (Grouped loosely by topic.)

ARMY COMMAND

High Command must have a representative from each of the orders
-DoWN Book III, Chapter 2

Army commander is the final authority.
-DoWN Book III, Chapter 11

DEFINITIONS

Enemy: any opposing force that attempts to obstruct a knight in their mission
-DoWN Book III, Chapter 2

Conduct

• Insubordination, failure to obey orders, masquerading as a knight, and cowardice are all offenses
• Do not take life needlessly.
• Fight only in defense of themselves or others
• Conduct that impinges upon the honor of the Knighthood as a whole is a serious offense
• Contests of honor forbidden in time of declared war
• Disobeying an order from a superior is inexcusable. (Doesn’t say if this applies only to lawful orders.)

-DoWN Book III, Chapter 2

Participating in Lost Battles would have been a violation of the Measure.
(Is this a prohibition against starting a war in general or just against initiating a battle in a place that is likely to lead to civilian casualties? If it’s a general prohibition against striking first then it might explain why the Knights never attacked Storm’s Keep in the years leading up to the Chaos War.)
-DoWN Book III, Chapter 4

Prohibition against knights fighting among themselves
-DoWN Book III, Chapter 10

Conspiracy is an offense
-DoWN Book III, Chapter 11

A knight may not travel in disguise
-DoFS, Book I, Chapter 6
(Note: subsequent books establish an exception to this prohibition if concealing the knight’s identity is necessary to complete an approved quest of honor)

Theft is evil
-The Soulforge, Book IV, Chapter 12

If a person is aware of law breaking and does nothing to stop it they are just as responsible as the lawbreaker
-The Soulforge, Book IV, Chapter 15

Spying on friends goes against the Measure
-DotDD, Book I, Chapter 5

Knights must support their superiors in word and deed.
-DotHS, Book I, Chapter 5

Knight cannot depart on long journey without approval of their superior
-DotHS, Book I, Chapter 6

Fulfillment of a quest of honor undertaken with sanction from the Knight’s Council should be a knight’s first priority. Knight can conceal their identity if necessary to succeed at such a quest
-DotHS, Book II, Chapter 1

Impugning the reputation of a noblewoman is against the Measure
-DotHS, Book II, Chapter 3

Knight’s duty is to thwart and confound their foes
-DotHS, Book II, Chapter 5

Forgive those who wrong you
-DotHS, Book II, Chapter 6

In time of warfare all personal animosities must be put aside
-DotHS, Book III, Chapter 7

Lies of omission violate the Measure
-LoH, Chapter 4

Suicide is against the Measure
-LoH, Chapter 25
(This goes against DoAT where Sturm stated that suicide was acceptable to the Solamnics, but it’s certainly plausible enough that cultural norms would have changed in the 13 centuries between Huma’s time and Sturm’s.)

Knight’s Council

Presided over by 3 knights (one from each order) who sit at a table carved with symbols of the Knighthood
Convened for purposes of determining strategy, assigning orders, selecting a warrior lord prior to battle, hearing charges of unknightly conduct, honoring those who performed valiantly, and settling questions concerning the Measure
All knights not on duty who want to may attend
Those that wish to speak stand in a cleared area in front of the presiding knights
Oath is recited at start of meeting
Knight’s Hymn is sung if the meeting is a joyous occasion
-DoSF, Book III, Chapter 1

Knight’s Trial

• Grand Master, High Clerist, High Justice preside over Knight’s trials
• 20 knights witness Knight’s Trial
• These witnesses are to remain silent.
• Knight has the right to answer accusations against him
• Knight has a right to call witnesses in his defense
• Absent corroborating witnesses, word of a knight must be believed over a squire
• Black roses wrapped around knight’s sword if they are found guilty.

-DoWN Book III, Chapter 2
(Uncertain if the last provision is actually part of the Measure or if it is just a Solamnic custom.)

Knighting Ceremony

Knight is to spend the night before the ceremony in prayer and meditation
-DoWN Book III, Chapter 10

Leadership

Commander should be an inspiration to their troops
-DotHS, Book III, Chapter 14

A leader never shouts, never loses their calm demeanor, never wavers or doubts, never shows fear
-DotHS, Book III, Chapter 14

Religion

All that die in service of their country will be rewarded in the afterlife
-DotVM, Book I, Chapter 10

Knight must have faith.
Measure also speaks of knights being able to cast divine magic spells.
Measure does not reference specific gods.
-DotHS, Book I, Chapter 5
(The last one seems rather odd for an organization that is supposedly dedicated to three specific gods. I suspect the Measure might have been rewritten after the Cataclysm to remove explicit references to the old gods.)

Spies

Forbids the use of spies
-DoFS, Chapter 28, DotVM Book I, Chapter 8
(This seems at odds with the Legends Trilogy where Gunthar had a spy network operating in Dragonarmy territory.)

Wizards

Declared enemies of the Knighthood
-The Soulforge, Book I, Chapter 4

Women

No prohibition against women becoming knights
-DoSD, Book I, Chapter 7

Duty of the lady wife of a knight to feed the poor and tend to the sick of the manor
-The Soulforge, Book V, Chapter 1

Miscellaneous

Ritual words that must be stated to an army commander departing on a mission
-DoWN Book III, Chapter 2

-Benches for meetings must be polished
-DoWN Book III, Chapter 6

-No provision to quickly remove a commander from their position even if the commander has gone insane.
-DoWN Book III, Chapter 10

-Honorary knights have same authority as actual knights
-TotT, Book II, Chapter 13

-Seniority base by age rather than rank
-TotT, Book II, Chapter 13
(Unclear if this provision is taken seriously as aside from being incredibly stupid, it seems to contradict what was previously established in DoWN since if the older knights can override younger knights regardless of the younger knight’s superior rank then any knight older than Derek Crownguard could have cancelled his suicidal attack.)

Last wishes of the dying are sacred and should be fulfilled if mortally possible.
-DoFS, Book I, Chapter 6
(I would assume the dying wish must not require the knight to do anything dishonorable or immoral but that’s not explicitly stated.)

Measure has provisions for forming a Grand Circle even when a quorum of knights is not available. No details on what those provisions are.
-DotHS, Book I, Chapter 5

“A knight should walk openly in the sunshine, proudly proclaiming his nobility to the world.”
-DotHS, Book II, Chapter 1

“Know your enemy”
-DotHS, Book III, Chapter 7
(Yet spying is prohibited?)

Knight making someone a Squire clears them of all prior misconduct that might otherwise bar them from becoming a knight
-DotHS, Book III, Chapter 11
(Note: not explicitly stated to be in the Measure, but it is a rule the Solamnic Knights follow and thus is almost certainly in the Measure)