https://en.wikipedia.org/wiki/Biblical_manuscript#Gregory-Aland
Gregory–Aland
Caspar René Gregory published another cataloging system in 1908 in Die griechischen Handschriften des Neuen Testaments, which is the system still in use today. Gregory divided the manuscripts into four groupings: papyri, uncials, minuscules, and lectionaries. This division is partially arbitrary. The first grouping is based on the physical material (papyrus) used in the manuscripts. The second two divisions are based on script: uncial and minuscule. The last grouping is based on content: lectionary. Most of the papyrus manuscripts and the lectionaries before the year 1000 are written in uncial script. There is some consistency in that the majority of the papyri are very early because parchment began to replace papyrus in the 4th century (although the latest papyri date to the 8th century). Similarly, the majority of the uncials date to before the 11th century, and the majority of the minuscules to after.[19]
"Gregory assigned the papyri a prefix of P, often written in blackletter script (𝔓n)"
P=Papyrus
Check out GA P17…
https://en.wikipedia.org/wiki/Papyrus_17
Papyrus 17 (in the Gregory-Aland numbering), signed by 𝔓17, is an early copy of the New Testament in Greek. It is a papyrus manuscript of the Epistle to the Hebrews, but only contains verses 9:12-19. The manuscript has been paleographically assigned to the 4th century.[1] However, according to Philip Comfort it is from the late 3rd century.
https://www.biblegateway.com/passage/?search=hebrews%209%3A12-19&version=NIV
Hebrews 9:12-19
New International Version
12 He did not enter by means of the blood of goats and calves; but he entered the Most Holy Place once for all by his own blood, thus obtaining[a] eternal redemption. 13 The blood of goats and bulls and the ashes of a heifer sprinkled on those who are ceremonially unclean sanctify them so that they are outwardly clean. 14 How much more, then, will the blood of Christ, who through the eternal Spirit offered himself unblemished to God, cleanse our consciences from acts that lead to death,[b] so that we may serve the living God!
15 For this reason Christ is the mediator of a new covenant, that those who are called may receive the promised eternal inheritance—now that he has died as a ransom to set them free from the sins committed under the first covenant.
16 In the case of a will,[c] it is necessary to prove the death of the one who made it, 17 because a will is in force only when somebody has died; it never takes effect while the one who made it is living. 18 This is why even the first covenant was not put into effect without blood. 19 When Moses had proclaimed every command of the law to all the people, he took the blood of calves, together with water, scarlet wool and branches of hyssop, and sprinkled the scroll and all the people.
It's about proving the death of Jesus, so that the covenant with God, which was granted into trust, can be released to its beneficiaries. The invisible enemy is the Trustee(s) of God's covenant.